TT 

1 5 5 

.?5 




Class 



Book. 



Copyrights 



COPYKIGHT DEPOSrr 



AMATEUR ME6flflN16S 

A BOOK 

FOR OLD AND YOUNG WHO LIKE 
TO MAKE THINGS 



"Written So You Can Understand It" 



Reprinted from POPULAR MECHANICS 



TELLS HOW TO MAKE 

Home-Made Telescope, Aquarium, Telegraph Instruments, Paddle Boat, 
Wireless Telegraph, Small Auto, Box Kite, Water Motor, Electric 
Furnace, Microscope, Book-Binding, Electroplating, China Kiln, 
Acetylene Gas Generator, Steam Engine, Tricks for Par- 
lor Magic, Bobsled, Silhouettes, Jump Spark Coils. 
Induction Coils, Rheostats, Lathe, Foundry 
Work at Home, Etc., Etc. 



CHICAGO 
POPULAR MECHANICS 

Copyrighted 









LIBRARY of CONGRESS. 
Two Copiet Recavac 

jan 23 ) yob 

CLA*8A_^ XXc Mh 
f COPY 8. 



Copyrighted 1907 

by 

H. H. WINDSOR 



CONTENTS 



Accelerometer, Simple '< 

Acetylene Gas Generator, Home-Made 7 

Alarm. Callers' Approach 2 

Alarm. Cheap Fire 

Alarm, Combined Door-bell and Electric I 

Alarm. Handy Electric i 

Amber. Imitation t 

Ammeter, How to Make £ 

Annunciator, Home-Made £ 

Aquarium, How to Make an 2 

Arc Light, Home-Made - 

Athletics for Young Men i 

Auto, Young Mechanic Builds Successful.... - 

Ball, Hollow, How to Make t 

Batteries, Connecting to Give Any Voltage. . 1 

Battery. Home-Made Grenet ! 

Battery Switch - 

Battery, Thermo, How to Make - 

Battery Zincs, To Use Old i 

Bell, Return Call, with One Wire f 

Bicycle Power for Running Miniature Trains. 1 

Boat, Paddle. How to Make i 

Bob-Sled Hinge ' 

Book Shelf, Easily Made c 

Bracket Saw. Cheap. How to Make 1 

Brazing, Flux for f 

Cabinet, Home-Made Disc 7 

Camera, Hand, Enlarging with a 7 

Camera Holder, Blackiead for Grooves in.... - 

Camera, Pictures Without : 

Cannon, How to Make Z 

Cannon, Toy, To Discharge by Electricity... Z 

Card Puzzle, Turning. .. .-. '. i 

Card Trick, Mechanical .' ( 

Cards. Mechanical Tricks with : 

Chicken Feeder. Alarm"Ciock ,. ; 

Circuit Breaker for Induction Coils i 

Club- House. Underground 

Cock, Three-Way. for Small Model Work.. .. i 

Compressed Air Phenomenon. Curious 

Cup and Saucer Rack, How to Make 7 

Cup, To Balance on a Knife £ 

Current Reverser, Simple 1 

Dogs and Cats. To Keep Away from Garbage 

Can ' 

Dogs. To Drive Away 

Door Opener. Electric - 

Draft Opener, Automatic 1 

Electric Blue Light Experiment t 

Electric Lighting. Miniature 2 

Electric Lamps. Experiments with £ 

Electric Light Circuit. Easy Experiments 

with I 

Electrical Experiment, Interesting £ 

Electricians' Don'ts £ 

Electro-Plating. Easy Method of £ 

Electroscope. How to Make 2 

Fire Screen, How to Make 7 

Foundry Work at Home. 

Part I— Equipment i 

Part II— How to Make a Mold ■- 

Part III — Melting and Pouring '- 

Furnace. Dcor Opener for 

Furnace Draft. Alarm Clock to Pull Up 2 

Furnace. Small Brass. To Build 1 

Furnace. Small Electric, How to Make 7 

Galvanoscope. How to Make 21. £ 

Gasoline Burner for Model Work 7 

Gear Wheels. Small. To Make Without a 

Lathe £ 

Grape Arbor. How to Build 7 

Gravity Batteries. Why Fail to Work 2 

Grocery Memorandum, How to Make £ 

Hammer, Experiment with Two-Foot Rule 

and £ 

Hammock, Barrel Stave i 

Hydrogen Generator, Constant Pressure £ 

Hydrogen Generator. Small Electrical 2 

Hygrometer. How to Make A 

Ice Chisel, Handy A 

Ice, Peculiar Properties of £ 

Incandescent Lamp. Lighting with Induction 

Coil A 

Ink, Black Ruling £ 

Interrupter. How to Make an £ 

Iron Rust. To Remove from Cloth t 

Jump Spark Coil, How to Make £ 



Kite, Box, How to Make A 

Language, How to Make a New 2 

Lathe. How to Make 3 

Lightning Flash. Photographs E 

Lock, Another Electric 2 

Lock, Automatic 1 

Lock. Combination, How to Make £ 

Lock, Electric, for Sliding Door 2 

Lock, Home-Made Pneumatic 3 

Lock, Simple Electric £ 

Lock, Spring, Protection of £ 

Locomctive, Model £ 

Locomotive, Neat Model £ 

Magazines. How to Bind £ 

Magic. Parlor, for Winter Evenings 1 

Medical Induction Coil, How to Make 7 

Microscope Without a Lens i 

Motor, Battery. Controller and Reverse for.. £ 

Motor, Controller for Small 2 

Motor, Small, Reversing 1 

Motors, Small, Direct-Connected Reverse for 2 

Mouse Trap, Novel 7 

Music Cabinet, How to Make £ 

Nail Holes, Filling 2 

Negative, To Make Without Plate or Film., £ 

Nickel, Polish for £ 

Optical Illusions 36, A 

Pantograph, How to Make £ 

Pen, Breaking in a New £ 

PepDer's Ghost Illusion, Miniature £ 

Phonograph Horn. Paper, How to Make £ 

Phonograph Music. To Transmit to a Dis- 
tance C 

Photograph a Man in a Bottle, To 2 

Photograph on Apples. How to £ 

Photographs "Freak." How to Make £ 

Pictures. To Make Four on One Plate £ 

Pipe Fittings. Uses for A 

Porch Chair. How to Make £ 

Pottery Kiln, Home-Made 7 

Powder, To Explode with Electricity £ 

Prince Ruoert's Drops £ 

Pump, Rotary, How to Make 7 

Railroad President. Youngest in the World.. 2 

Rain Gauge, How to Make -1 

Relay Made from Electric Bell A 

Reversing Switch for Electrical Experiments 1 

Rheostat. Battery 7 

Rheostat. Water, How to Make 3 

Rheostat. Water, How to Make a Simple 7 

Sealing Wax Bent While Cold 

Sheet Metal. To Lubricate 5 

Silhouettes. How to Make 7 

Spit Turned by Water Power 3 

Squirrel Pest, Antidote for 3 

Steam Engine Built in Amateur Shop 4 

Steam Engine, Toy, How to Make 2 

Stream, To Cross on a Log 7 

Switch for Reversing a Current 9 

Table, Method of Lifting 1 

Telegraph. Cheap, for Learners 5 

Telegraph Key and Sounder, How to Make.. 3 

Telegraph Line. One-Wire 7 

Telegraph Line, Simple Open Circuit 3 

Telephone, Receiver, Home-Made 4 

Telephone, Singing 

Telescope. Farmer's Boy Builds 1 

Time Switch, Automatic 5 

Toboggan Sled, How to Build 1 

Top. Optical 2 

Trap for Small Animals 9 

Trees, Burning Inscriptions on 5 

Water-Colors. To Prevent from Crawling 3 

Water Motor. Home-Made 6 

Windmill. Musical 6 

Window Boxes. Rustic 1 

Window Conservatory 7 

Wireless Coherer. Easily Made 2 

Wireless System, Novel 6 

Wireless Telegraph 5 

Wireless Telegraph, How to Make an Effi- 
cient 6 

Wireless Telegraph Messages, i o Receive 

with a Telephone 5 

Wireless Telegraphy. To Make a Jump Spark 

Coil for 5 

Writing with Electricity 



AN UNDERGROUND CLLB=HOLSE 



Nearly every boys' club wants a place to 
meet and it was for this purpose that the 
underground house here shown was con- 
structed. The house is built in a hill which 
was first excavated, as shown in Fig. 1, the 
dirt being thrown on each side, to be used 
later for banking and covering the roof. 

The house consists of two principal parts: 
the entry. Fig. 2. and the club room. Fig. 3. 
This may be made any length desired, but 
should not be more than 5 or 6 ft. wide, as 
a greater width would require cross beams 



of furniture that are usually required. These 
may be either home-made, as shown, or may 
be obtained from the old furniture discarded 
from the home. The door. Fig. 6, is pro- 
vided with a secret lock which consists of 
a latch, A, supported on a strong frame. B, 
and swinging on a pivot near the center. 
A string, C. is fastened to the latch and 
terminates in a ring, D, which is placed in 
a location known only to the members of 
the club. A light spring or rubber band 
may be used to make the latch spring over 




Details of Construction and Equipment oi UnJerji 



to support the roof and would thereby make 
the construction much more complicated. 

The lumber used should be about 1 in. 
thick and should be fastened together in a 
good workmanlike manner. This is espe- 
cially true of the roof, which is required to 
support the weight of the earth above in 
addition to the weight of any possible in- 
truder and which, if too weak, will endanger 
the occupants of the house. The boards 
should be nailed across the short way to 
give greater strength and it is well to nail 
a long board along the middle the entire 
length of the roof. 

In Figs. 4 and 5 are shown the articles 



in front of the door, and when the door is 
closed it will lock itself. 

The longitudinal section of the complete 
house is shown in Fig. 7. The ventilator, A. 
can be made of either wood or stove pipe 
and if desired can have a small cover over 
the top to prevent rain coming in. If a 
stove is used, a pile of burnt wood can be 
placed around the stack, as shown at B, so 
that the suspicions of passers-by will not 
be aroused in any way. Also a bush, C, 
transplanted at the entrance, will hide the 
door. 

An underground club-house of this kind 
will prove a source of mystery to those 



POPULAR MECHANICS 



uninformed of the secret entrance.— Con- 
tributed by Charles Edwards, Jr., 2623 E. 
Preston St., Baltimore, Md. 

♦ • ♦ 

SEALING WAX BENT WHILE COLD 



If a piece of sealing wax is supported in 
a horizontal position by one end, as shown 
at A in the sketch, it will gradually bend to 
the shape indicated by the dotted lines, B. 



^^SL * 


C — ^--^' ~^sN 




, B 

i> 




I L^>^ 


L_ Ky^ v 


> <g 4 



Bending Cold Sealing Wax 

To attempt bending it with the hands would 
result in breaking it unless a steady pressure 
were applied for a long time. This peculiar 
property is also found in ice. 



A CHEAP FIRE ALARM 



An electrical device for the barn that will 
give an alarm in case of fire is shown in the 
accompanying diagram. A is a wooden 
block, which is fastened under the loft at 
a gable end of the barn; B is an iron weight 
attached to the string, C, and this string 
passes up through the barn to the roof, then 
over a hook or pulley and across the barn, 
under the gable, and is fastened to the oppo- 
site end of the barn. 

D D are binding posts for electric wires. 
They have screw ends, as shown, by which 
means they are fastened to the wooden 
block, A. They also hold the brass piece, 




E, and the strip of spring brass, F, in place 
against the wooden block. G is a leather 
strap, fastened to the weight. B, and the 
spring, F. connected to the latter by a small 
sink bolt. 

At the house an eleotric bell la placed 
wherever convenient. Several battery cells, 
of course, are also needed. Dry batter!* 
most convenient The battery cells and bell 
are connected in the usual manner, ami one 
wire from the bell ami one from the bat- 
tery are strung to the barn ami connected to 
the binding posts, D D. 

If a fire occurs in the hay mow the I 
will generally shoot toward the gable BOOH 
after it starts, ami will then burn the Rtrlng, 
C, which allows the weight. B, to fall ami 
pull the brass spring against the iron | 
E, which closes the circuit ami rings the 
bell that is in the house. 

If desired, the Btring can bo stretched 
back and forth under the roof several times 
or drawn through any place that is in dan- 
ger of fire. — Contributed by Geo. B. Wrenn, 
Ashland, Ohio. 

A CURIOUS COMPRESSED AIR 
PHENOMENON 



Push a pin through an ordinary business 
card and place the card against one end of 
a spool with the pin inside the bore, as 




Automatic Circuit-Closing Device 



Experiment with Spool and Card 



shown in the sketch. Then blow throuph 
the spool and it will be found that the card 
will not be blown away but will remain 
suspended without any visible support. This 
is explained by the fact that the air radiates 
from the center at a velocity which is nearly 
constant, thereby producing a partial vacuum 
between the spool ami the card. Can any 
of the readers of Mechanics for Young 
America devise a practical application of 
this contrivance? 

Mechanics for Young America, our iplandid 

book for boys. Only 25 centa. 



POPULAR MECHANICS 



A SINGING TELEPHONE 



Those who have not already tried the ex- 
periment may be interested to know that a 
telephone can be made to sing by holding 
the receiver about & in- from the trans- 




To Make a Telephone Sing 

mitter, as shown in the illustration. The 
experiment will work well on most tele- 
phones, but not on every one. 

When the receiver is placed in the posi- 
tion shown it acts like an ordinary buzzer, 
and the function of the transmitter will 
then be that of an interrupter. The slight- 
est movement of the transmitter diaphragm 
will cause an increased movement of the 
receiver diaphragm. This in turn will act 
on the transmitter, thus setting up sympa- 
thetic vibrations between the two, which ac- 
counts for the sound. 



DOOR OPENER FOR FURNACE 



The accompanying diagram shows an ar- 
rangement to open the coal door of a fur- 
nace. "When approaching the furnace with 
a shovelful of 
coal it is usu- 
ally necessary 
to rest the 
shovel on the 
top of the ash 
door, while 
the coal door 
is opened. 
With my de- 
vice it is only 
necessary t o 
press the foot 
pedal, which opens the door. After putting 
in the coal, pressing the pedal closes the 
door. The pulley in the ceiling must be 



H'nged 


f\ '- ^S 










% Door 


J 
1 




; 


\ 



placed a little in front of the door, in order 
to throw the door open after lifting it from 
the catch. 

A large gate hinge is used to hold the 
pedal to the floor. — Contributed by Edward 
Whitney, 18 E. Gorham St., Madison, Wis. 



WRITING WITH ELECTRICITY 



Soak a piece of white paper in a solution 
of potassium iodide and water for about a 
minute and then lay on a piece of sheet 
metal. Connect the sheet metal with the 
negative or zinc side of a battery and then, 
using the positive wire c as a pen, write your 
name or other inscription on the wet paper. 
The result will be brown lines on a white 




Electrolytic Writing 

background. — Contributed by Geo. W. Fry, 
1250 Locust St.. San Jose, Cal. 



TO DRIVE AWAY DOGS 



The dogs in my neighborhood used to 
come around picking up scraps. After I 
connected up my induction coil, as shown 
in the sketch, we were not bothered with 
them. A indicates the ground; B. switch; 
and C, a bait of meat, or a tempting bone. — 
Contributed by Geo. W. Fry, 903 Vine St., 
San Jose, Cal. 



i:h4 b 



-£ 



Shocking Machine 



POPULAR MECHANICS 



HOW TO BUILD A TOBOGGAN SLED 



li> A. Itoette 



The first object of the builder <>f a sled 
should be to have a "winner." both in speed 
and appearance. The accompanying instruc- 
tions for building a sled are designed to 
produce these results. 

The sled completed should be 15 ft. 2 in. 
long by 22 in. wide, with the cushion about 
1") in. above the ground. For the baseboard 
select a pine board 15 ft. long, 11 in. wide 
and L' in. thick, and plane it on all edges. 



length of the sled from the bat i t" the ante 
front from 

falling "ut. Sc pig. i Por the back of the 
sled nee the upper part of a child's high 
chair, taking out the spindlea and resetting 
them in the rear end oard 

Cover up ii ■ rltfe a 

piece of galvanised iron. 

The construction of the runners is shown 
ai Pigs. _■ and ::. The stock required for 







i 




v 


















"-• 




- 






*! 






i 




f l ;e| I 



I** 



Efflfi 




Constructing a " Winner" Tubounan Sled 



Fit up tho baseboard with ten oak foot 
rests. 22 in. long, 3 in. wide and :: , in. thick. 
Fasten them on the underside of the base- 
board at right angles to its length and 16 
in. apart, beginning at the rear. At the 
front 24 or 26 in. will be I. ft without cross- 
fitting on the auto front. On the 

upper side of the cross bars at their ends 
on each side screw a piece of oak l In. I 
i in. by 14 ft. long. On the upper dde of the 

baseboard at its edge OB eat h side screw an 
oak strip 3 in. wide by % in. thick and the 



them is oak. | W m. x 1 ' , 

in., two pieces 14 In, i S In \ i ', in., two 
I in. \ 8 in \ I In and ft 

1 I in \ I in. x 1 in 

together with i In. Ions 

Use UO nails. 

enough. In proportioning then, the points 

A. H and ('. Pig. 2, are important. For tlio 

front rum 

SO in.; B, 4 in C. 15% in., and for I 

runners: A. Ml in . M. 7 in . C, 16% in The 



POPULAR MECHANICS 



11 



straight line and the holes for them care- 
fully centered. A variation of jfe in. one 

way or another would cause a great deal of 
trouble. For the steel runners use 3 x-in. C. 
R. steel flattened at the ends for screw 
holes. Use no screws on the running sur- 
face, however, as they ''snatch" the ice. 

The mechanism of the front steering gear 
is shown at Fig. 3. A -"Vim steel rod makes 
a good steering rod. Flatten the steering 
rod at one end and sink it into the wood. 
Hold it in place by means of an iron plate 
drilled to receive the rod and screwed to 
block X. An iron washer, Z, is used to re- 
duce friction; bevel block K to give a 
rocker motion. Equip block X with screw 
eyes, making them clear those in the front 
runner, and bolt through. For the rear run- 
ner put a block with screw eyes on the base- 
board and run a bolt through. 

Construct the auto front (Fig. 4) of %-ia. 
oak boards. The illustration shows how to 
shape it. Bevel it toward all the sides and 
keep the edges sharp, as sharp edges are 
best suited for the brass trimmings which 
are to be added. When the auto front is in 
place enamel the sled either a dark maroon 
or a creamy white. First sandpaper all the 
wood, then apply a coat of thin enamel. Let 
stand for three days and apply another 
coat. Three coats of enamel and one of 
thin varnish will make a fine-looking sled. 
For the brass trimmings use No. 27 B and S 
sheet brass 1 in. wide on all the front edges 
and pieces 3 in. square on the cross bars to 
rest the feet against. On the door of the 
auto front put the monogram of the owner 
or owners of the sled, cutting it out of sheet 
brass. 

For the steering wheel procure an old 
freight car "brake" wheel, brass plated. 
Fasten a horn, such as used on automobiles, 
to the wheel. 

Make the cushion of leather and stuff it 
with hair. The best way is to get some 
strong, cheap material, such as burlap, sew 
up one end and make in the form of an ob- 
long bag. Stuff this as tightly as possible 
with hair. Then get some upholstery but- 
tons, fasten a cord through the loop and 
bring the cord through to the underside of 
the cushion, and fasten the button by slip- 
ping a nail through the knot. Then put a 
leather covering over the burlap, sewing it 
to the burlap on the under side. Make the 
cushion for the back in the same way. On 
top of the cushion supports run a brass tube 
which will serve the double purpose of hold- 
ing the cushion down and affording some- 
thing to hold on to. 



If desired bicycle lamps may be fastened 
to the front end, to improve the appearance, 
and it is well to have a light of some kind 
at the back to avoid the danger of rear-end 
collisions. 

The door of the auto front should be 
hinged and provided with a lock so that 
skates, parcels, overshoes, lunch, etc., may 
be stowed within. A silk pennant with the 
monogram on adds to the appearance. 

If desired, a brake may be added to the 
sled. This can be a wrought iron lever l x o 
in. by x 2 in. by 30 in. long, so pivoted that 
moving the handle will cause the end to 
scrape the ice. This sled can be made with- 
out lamps and horn at a cost of about $15. 
or with these for £2-5 and the pleasure derived 
from it well repays the builder. If the expense 
is greater than one can afford, several beys can 
share in the ownership. 

AUTOMATIC DRAFT OPENER 



A simple apparatus that will open the 
draft of the furnace at any hour desired is 
illustrated. The parts are: A, furnace; B, 
draft: C, draft chain; D. pulleys; E, wooden 
supports: F. vertical lever; G, horizontal 
lever; H, cord; I, alarm clock; J, weight. 
K shows where and how the draft is regu- 



r - = - --__-_-- 


.="■-•- 




/ 

A 

t 

f 



lated during the day. the automatic device 
being used to open it early in the morning. 
The spool on the alarm clock is fastened 
to the alarm key by sawing a slit across 
the top of the spool and gluing it on. "When 
the alarm goes off a cord is wound up on 
the spool and pulls the horizontal lever up. 
which releases the vertical lever and allows 
the weight to pull the draft open. — Con- 
tributed by Gordon Davis, 518 W. Dutton 
St., Kalamazoo, Mich. 



PO it LA R M ECH A MPS 



CONNECTING UP BATTERIES TO 
GIVE ANY VOLTAGE 



1 


ll 


II 


|-fe 






1 
















1 i 

9 


c 


D 




Batteries Connected to Give Any Voltage 
posts. When switch B is closed and A 



TO BUILD A SMALL BRASS 
FURNACE 



Referring to the illustration: A is a five- 
point switch (can be bome-made); 15 is ■ 
one-point switch and C and C arc binding 



is 



Bend a piece of stoul sheet Iron - 

in in. round mi tii.it the inside diameter is 

7 in. and then rivet tbe Ream. I 

round i> I •■ c e 

Of Bbeel iron 

t',.r the bot- 

i < mi. Make a 

bole a linn! 

the size of ■ 

shilling in the 

Side ^ in. 

from the hoi 
torn. This is 
for the pur- 
pose of blow- 
big. 

Line the 
furnace, bot« 
t o in a n d 
sides, with 
fireclay to a 
depth of '_. in. 
Use charcoal to bnrn and an ordinary bel- 
lows for blowing, s.iys the Model Bng 
London. The West blast is obtained by 
holding the nozzle or the bellows about an 
inch from the hole, instead of clos< 




Brass Fnrnace 



on No. 1, you have the current of one bat- 
tery; when A is on No. 2 you receive the 
current from two batteries; when on No. 3 
from three batteries; when on No. 4 from 
four batteries, and when on No. 5 from 

five batteries. More batteries may be con- 
nected to each point of switch B. 

I have been usim: the same method for 
my water rheostat (home-made). I have 



BOB=SLED HINGE 



The illustrations show h<>w in make a 
good bob-sled binge which will hold the slt^l 
very firmly, but allow it t.. move up and 
down. The binge Should be made of iron 
and of the dimensions indicated in the 
sketches. Fig. :>, passes through the hole, X. 



1 
1 




**• 


* . 




Fig. 1 


frf | 


- AT- - 


% 


x 








Pig. 2 


X 



MSI 

±_ 



Fig. 3 



/J — 







Hinge for a Bob-Sled 

the jars of water where the batteries are v is a hole to bend a nail through. 

and the current coming in at a and b. hinge <an be mad.- for I I 00 

Contributed by Eugene v. Tattle, Jr., New- trlbuted by Barold i; Bullock, MS Richmond 

ark, Ohio. .-met, Anpleton, w la 



POPULAR MECHANICS 



PARLOR MAGIC FOR WINTER EVENINGS 



By C. H. Claudy 



tosses it 
cave, but 



You are seated in a parlor at night, with 
the lights turned low. In front of you, be- 
tween the parlor and the room back of it, 
is an upright square of brightly 
burning lights, surrounding a 
perfectly black space. The ma- 
gician stands in front of this, in 
his shirt sleeves, and after a 
few words of introduction pro- 
ceeds to show the wonders of 
his magic cave. Showing you 
plainly that both hands are 
empty, he points with one finger to the box, 
where immediately appears a small white 
china bowl. Holding his empty hand over 
this bowl, some oranges and apples drop 
from his empty hand into the bowl. He 
removes the bowl from the black box, or 
cave, and hands its contents round to the 
audience. Receiving the bowl again, he 
into the 
it never 
reaches the floor — 
it disappears in mid- 
air. 

The illusions he 
shows you are too 
many to retail at 
length. Objects ap- 
pear and disappear. 
Heavy metal ob- 
jects, such as forks, 
spoons and jack- 
knifes, which have 
been shown to the 
audience and which 
can have no strings 
attached to them, 
fly about in the box 
at the will of the 
operator. One thing 
changes to another 
and back again and 
black art reigns su- 
preme. 

Now all this "mag- 
ic" is very simple 
and requires no 
more skill to pre- 




pare or execute than any clever boy or girl 
of fourteen may possess. It is based on the 
"Black Art" performance of the famous 
Hermann, and relies on a principle of op- 
tics for its success. To prepare such a magic 
cave, the requisites are a large soap box, a 
few simple tools, some black paint, some 
black cloth, and plenty of candles. 

The box must be altered first One end is 
removed and a slit, one-third of the length 
from the remaining end, cut in one side. 
This slit should be the width of the box 
and about five inches wide. On either side 
of the box, half way from open end to closed 
end, should be cut a hole, just large enough 
to comfortably admit a hand and arm. 

Next, the box should be painted black 
both inside and out, and finally lined inside 
with black cloth. This lining must be done 
neatly — no folds must, show and no heads 
of tacks. The inte- 
rior must be a dead 
black. The box is 
painted black first 
so that the cloth 
used need not be 
very heavy and con- 
sequently, inexpen- 
sive; but if the cloth 
be sufficiently thick, 
no painting inside 
is required. The 
whole inside is to be 
cloth-lined, floor, top, 
sides and end. 

Next, the illumi- 
nation in front 
must be arranged. 
If you can have a 
plumber make you 
a square frame of 
gas piping, with tiny 
holes all along it for 
the gas to escape 
and be lit, and con- 
nect this by means 
of a rubber tube to 
the gas in the house, 
so much the better; 



14 



POPULAR MECHANICS 



hut a plentiful supply of short candles will 
do just as well, although a little more 
trouble. The caudles must be close together 
and arranged on little brackets around the 
whole front of the ••cave" (see diagram), 
and should have little pieces of bright tin 
behind them, to throw the light towards the 
audience. The whole function of these can- 
dles is to dazzle the eyes of the spectators 
and prevent them seeing very far into the 
Mack box. 

Finally, you must have an assistant, who 
must be provided with either black gloves 
or black bags to go over his hands and 
arms, and several black drop curtains, at- 
tached to sticks greater in length than the 
width of the box, which are let down 
through the slit in the top. 

The audience room should have only low 
lights; the room where the cave is should 
be dark, and if you can drape portieres be- 
tween two rooms around the box (which, of 
course, is on a table) so much the better. 

The whole secret of the trick lies in the 
fact that if light be turned away from any- 
thing black, into the eyes of him who looks, 
the much fainter light reflected from the 
black surface will not affect the observer's 
eye. Consequently, if when the exhibitor 
puts his hand in the- cave, his confederate 
behind inserts his hand, covered with a 
black glove and holding a small bag of 
black cloth, in which are oranges and apples, 
and pours them from the bag into a 
dish, the audience sees the oranges and 
apples appear, and does not see the black 
arm and bag against the black background 
at all. 

The dish appears by having been placed 
in position behind a black curtain, which 
is snatched swiftly away at the propec mo- 
ment by the assistant. Any article thrown 
into the cave and caught by the black hand 
and concealed by a black cloth appears to 
disappear. Any object not too large can be 
made to "levitate" by the same means. A 
picture Of any one present may be made ,o 
change into a grinning skeleton by suddenly 
screening it with a dropped curtain, while 
another curtain Is swiftly removed from 
over a pasteboard skeleton, which can be 

made to dance either by strings, or by the 
black veiled hand holding on p. it from be 
hind, and the skeleton can change to a white 
cat 
Bui illusion- Buggest themselves. There 

Is no end to the effects which can be had 
from this simple apparatus, and if the ape* 
rators are sufficiently well drilled the re- 



sult is truly remarkable to the uninitiated. 
The illusion, as presented by Hermann, waa 

identical with this, only he, <<1 course, had 

a big Btage, ami people clothed in black t" 

creep abOUt ami do his bidding, while here 

the power behind the throne is but a black 

veiled hand and arm. It can be made even 

more complicated by having two assistants, 

one on each side of the box, which 
why it was advised that two bolei be COt 
This enables an absolutely instantaneous 

change as one uncovers the object at the 

moment tic- Becond aS8l8tan1 covers aim re- 
moves the other. 

It is important that the assistants remain 
invisible throughout, and it portieres are Im- 
possible, a screen must l.e used. Hut any 
boy Ingenious enough to follow these simple 

instructions, will not need to be told that the 
Whole SUCCCSS of the exhihition depends 
upon the absolute failure of the audience to 
understand that there is more than one con- 
cerned in bringing about the curious effects 
which are seen. The exhibitor should be 
a boy who can talk; a good "patter" — as the 
magicians call it— is often of more value 
than a whole host of mechanical effects and 
helpers. It Is essential that the exhibitor 
and his confederate he well drilled, so that 
the latter can produce the proper effects at 
the proper cue from the former, finally, 
never give an exhibiton with the ••cave" un- 
til you have watched the illusions from the 
fronl yourself; so that you can determine 
whether everything connected with the drap- 
ing is right, or whether some stray bit of 
light reveals what you wish to conceal. 



TO KEEP DOGS AND CATS AWAY 
FROM THE GARBAGE CAN 



Last summer 1 was annoyed a great deal 
by dogs upsetting our garbage can on the 




lawn, but finally executed a plan that rid 

the yard of them in one afternoon. 

I tirst secured a magneto out of an old 

telephone, then 4lo\e a spike ill a Wa Inp 



POPULAR MECHANICS 



place under the porch, attached a wire to 
the spike and run the wire to one of the 
poles of the magneto. Then I set the gar- 
bage can on some blocks of wood, being 
careful not to have it touch the ground at 
any point I next ran a wire from the 
other pole of the magneto to the can. wrap- 
ping the wire around the can several times. 
Then I sat down on the porch to wait. 

It was not long before a big greyhound 
came along., putting his forepaws on the 
top of the can to upset it. At the same 
instant I gave the magneto a quick turn, 
which sent the dog away a very surprised 
animal. This was repeate sevei - times dur- 
ing the afternoon with other dogs with the 
same result— Contributed by Gordon T. 
Lane, Crafton. Pa. 



AN AUTOMATIC LOCK 



The illustration snows an automatic lock 
operated by- electricity, one cell being suf- 
ficient When the circuit is broken a 
weight, A. attached to the end of the arma- 
ture, B, tends to push the other end of the 
armature into the screw eye or hook, C, 



NEW METHOD OF LIFTING A 
TABLE 

To perform this feat effectively the little 

device illustrated will be required. To make 
it take a sheet-iron band, a, % in. wide and 
attach a strap to fasten on the forearm be- 
tween the wrist and elbow. Put a sharp 
needle point, B, through the sheet-iron so 
that it extends K in. outward. Make one of 
these pieces for each arm. 

In lifting the table first 
show the hands unprepared 
to the audience and also a 
light table, removing the 
cover to show that the sur- 
t. .- -_'_ the table is not pre- 
pared in any way. Then re- 
place the table, rest the hands 
upon it and at the same time press the 
needle points in the arm pieces into the 
wood of the table, which will be sumeient 
to hold it, says a correspondent of the 
Sphinx. Then walk down among the audi- 
ence. 





SIMPLE CURRENT REVER5ER 



On a block of hardwood draw" a square 
(Fig. 1) and drill a hole in each corner of 
the -^uare. Fill these holes with mercury 
and connect them to four binding posts 
(AAA A, Fig I 

On another block of wood fasten two 
wires, as shown in Fig-. 1. so that their ends 
can be placed in the holes in the first - 
block. Then connect up with the motor 
and battery as in Fig: I "ten the block 



Automatic Electric Lock ior Doors 

which is in the door, thus locking the door 
To unlock the door, merely push the but- 
ton, E. The magnet then draws the arma- 
ture out of the screw eye and the door is 
unlocked. The dotted bine at D shows the 
position of the armature when the en I 
is implete and the door unlocked. The 
weight must be in proportion to the site 
of the magnet If it is not, the door will 
not lock, or would remain locked. The but- 
ton can be hidden, as it is the key to the 
lock.— Contributed by Claude B. Melchoir. 
Hutchison, Minn. 




For Reversing a Current 
is placed on with the big arrow. A. pointing 
as in the direction indicated in Fig. 3, the 
current flows with the small arrows To 
reverse turn through an angle of 90 degrees 
(Fig. 4).— Contributed by F. Crawford 
Curry, Brockville, Ontario, Canada. 



16 POPULAR MECHANICS 

BICYCLE POWER FOR RUNNING MINIATURE TRAINS 



Remove the front wheel 
from the bicycle and In its 
place fix a seat as at A in 
the sketch. Take the tire 

off the back wheel and run 
a small leather belt around 
the wheel to transmit power 
to the dynamo, B, which is 
connected up, as shown, and 
causes the little electri< car 
to run when the wheel is 
operated. — Contributed by 
Clifford B. Brainerd, Chevy 
Chase, Md. 




Bicycle Power for Electric Railway 



RUSTIC WINDOW BOXES 



Instead of using an ordinary green 
painted window box why not make an artis- 
tic one in which the color does not clash 
with the plants contained 
in it but rather harmonizes 
with them and brings out 
the beauty of the foliage to 
the most advantage. 

Such a window box can 
be made by anyone having 
usual mechanical ability 
and will furnish more op- 
portunities for artistic and 
original design than many 
other articles of more com- 
plicated construction. 

The box proper should be 
made a little shorter than 
the length of the window to 
allow for the extra space 
taken up in trimming and 
should be nearly equal in 
width to the sill, as shown 
in Fig. 1. If the sill is In- 
clined, as is usually the 
case, the boi will require a 
greater height in front, to make it set level, 
as sh/>wn in Fig. 2. 

The box should be well nailed or screwed 
together ami should then be painted all 
over to make it more durable A number 
of '_. in. holes should he drilled in the bot- 
tom, thus allowing the excess water to run 
out ami prevenl rotting the plants ami box. 

Saving completed the bare bos it may be 

trimmed to BUil the fa my of the maker. 
The design shown in Fig. 1 is very simple 
and easy to construct but may be replaced 



with a panel or other design, one form 
of panel design is shown in I 

Trimming having too rough a surface will 




Artistic Window Boxes 
be found unsuitable for this work as it is 

difficult to fasten ami cannot be split as w. n 
as smooth trimming, it should be cv( the 
proper length before i»«-ii>^ spill ami should 

■ >n with brads. The half round 

of barrels will be found very useful 
in trimming, especially for Olllng-ia pur 

and by using them the operation of 
splitting is avoided. After the t>ox Is 

trimmed. th<' rustic work should I" 

nishf-1, in order t<» thoroughly presenrs it, as 
well as improve it« sppearsiMTB 



POPULAR MECHANICS 



Farmer's Boy Builds a Telescope and 
Discovers a Comet 



First, get two pieces of plate glass, 
6 in. square and 1 in. thick, and break 
the corners off to make them round, 
grinding the rough edges on a grind- 
stone. Use a barrel to work on, and 
fasten one glass on the top of it in the 
center by driving three small nails at 
the sides to hold it in place. Fasten, 
with pitch, a round 4-in. block of wood 
in the center on one side of the other 
glass to serve as a handle. 

Use wet grain emery for coarse 
grinding. Take a pinch and spread 
it evenly on the glass which is on the 
barrel, then take the glass with the 
handle and more it back and forth 
across the lower glass, while walking 
around the barrel; also rotate the 
glass, which is necessary to make it 
grind evenly. The upper glass or spec- 
ulum always becomes concave, and 
the under glass or tool works convex. 

Work with straight strokes 5 or 6 
in. in length; after working 5 hours 
hold the speculum in the sunshine and 
throw the rays of the sun onto a 
paper ; where the rays come to a point 
gives the focal length. If the glass is 
not ground enough to bring the rays 
to a point within 5 ft. the coarse 
grinding must be continued, unless a 
longer focal length is wanted. 

Have ready six large dishes, then 
take 2 lb. flour emery and mix in 12 
qt. of water; immediately turn the 
water into a clean dish and let settle 
30 seconds; then turn it into another 
dish and let settle 2 minutes, then 8 
minutes. 30 minutes and 90 minutes, 
being careful not to turn off the 
coarser emery which has settled. When 
dry, turn the emery from the 5 jars 
into 5 separate bottles and label. Then 
take a little of the coarsest powder, 
wetting it to the consistency of cream, 
and spread on the glass, work as be- 
fore (using short straight strokes H 




or 2 in.) until the holes in the glass 
left by the grain ernery are ground 
out ; next use the finer grades until the 
pits left by each coarser grade are 
ground out. When the two last 
grades are used shorten the strokes to 
less than 2 in. When done the glass 
should be semi-transparent, and is 
ready for polishing. 

When polishing the speculum, paste 
a strip of paper 1^ in. wide around 
the convex glass or tool, melt 1 lb. of 
pitch and turn on to it and press with 
the wet speculum. Mould the pitch 
while hot into squares of 1 in., with 
^-in. spaces, as in Fig. 1. Then warm 
and press again with the speculum, 
being careful to have all the squares 
touch the speculum, or it will not pol- 
ish evenly. Trim the paper from the 
edge with a sharp knife, and paint the 
squares separately with jewelers rouge, 
wet till soft like paint. Use a binger 
to spread it on with. Work the spec- 
ulum over the tool the same as when 
grinding, using straight strokes 2 in, 
or less. 

When the glass is polished enough 
to reflect some light, it should be tested 
with the knife edge test. In a dark 
room, set the speculum against the 



POPULAR MECHANICS 



wall, and a large lamp, L, Pig. 2, twice 
the focal length away. Place a large 
sheet of pasteboard, A. Fig. 8, with a 

small needle hole Opposite the hla/.e. 
by the side of the lamp. BO the ligW 
from the hla/.e will shim- nut,, the -lass. 

Place the speculum, S, Pig. 8, bo the 

r;ivs from the needle hole will he 

thrown to the left Bide of the lamp 
(facing the speculum ). with the knife 
mounted in a block of wood and edge- 
ways to the lamp, ae in K. Fig. ''■ The 
knife Bhould not he more than 6 in. 
from the lamp. Now move the knife 

across the rays from left to right, and 

look at the BpeCUlum with the eve on 

the righl side of the blade. When the 
focus is found, if the speculum is 
ground and polished evenly it will 
darken evenly over the surface as the 
knife Bhuts 'oil' the ligW from the 
needle hole. If not, the Bpeculum will 
show some dark rings, or hills. I f the 
glass seems to have a deep hollow in 
the center, shorter strokes should be 
used in polishing; if a hill in the cen- 
ter, longer strokes. The polishing and 
testing done, the speculum is ready to 
he silvered. Two glass or earthen- 
ware dishes, large enough to hold the 
speculum ami -J in. deep, must he pro- 
cured. With pitch, cemenl a strip of 
hoard 8 in. Ion- to the hack of the spec- 
ulum, and lav the Bpeculum face down 
in one of the dishes; fill the dish 

with distilled walei-. and clean the face 

of the Bpeculum with nitric acid, un- 
til the water will Btict to h m an un- 
broken film. 

The recipe for silvering the speculum 
is: 

Solution A : 

Distilled water \ <*• 

Sliver nitrate 100 gr. 

Solution B 

Distilled water I 01 

Caustic stick potasb (pure by alcohol). 100 gr. 

Solution C : 
Aqua ammonia. 

Solution i> 

Sugar loaf 

Nitric acid 

Alcohol (pure) 25 dr. 

Miz BOlution I > and make up 
oz. fluid with distilled water, pour into 

a bottle and keep for future use, ae il 
works better when old. 

Now take solution A and set aside 
in a small bottle one-tenth of it. and 




Details of Telescope Construction 

pour the rest into the empty dish ; add 
the ammonia solution drop by drop: 
a dark brown precipitate will form and 
subside ; -top adding ammonia solution 

as B i as the hath clears. Then add 

solut imi \k then ammonia until hath is 
clear. Now add enough of the solution 
A, that was sel aside, to bring the hath 
to a warm saffron color without destroy- 
ing its transparency. Then add l o 
of solution D and -nr until hath gTOWS 

dark. Place the Bpeculum face down 

in the hath and leave until the silver 
rises, then raise the speculum and rinse 
with distilled water. The small Hat 
mirror may he silvered the same way. 
When i\vy, the silver film may he pol- 
ished with a piece of chamois skin. 
touched with rouge, polishing with a 
light spiral stroke. 

Fig. :'» show- the position of the 
glasses m the tube, also how thi 
K. from a -tar are thrown to the e\v- 
I :. in flic side of the tuhe. Make 

the tuhe. I. of sheel iron, cover with 
paper and cloth, then paint to make a 
non-conductor of heat or cold. Make 

the mounting of good seasoned lumber. 

Thus an cm client 6-in. tel< - ope can 
he made at home, with an outlay of only 
a few dollars. My telescope is 64 in. 
long and coal me jus! *K>. hut I used 

all my spare time in one w inter in mak- 
ing it. I firsl began Btudying the 
heavens through a Bpy glass, hut an 
instrument such as I desired would 
on more than I could afford. 
Then I made the our described, with 
which I discovered a new comet nol 
before observed by astronomers. 
!•:. Hellish. 



POPULAR MECHANICS 



REVERSING SWITCH FOR ELEC = 
TRICAL EXPERIMENTS 



A home-made reversing switch, suitable 
for use by students of electrical and engi- 
neering courses in performing experiments. 
• n in the diagram. 

Referring to Fit:. 1. A represents a pine 
board 4 in. by 4 in. and a is a circular piece 
of wood about 34 in. square, with three brass 
strips, b\ tr. b\ held down on it~oy two 



. 


— 


.--' 








/ fv/ 








\ \' c 


T 


PJ j 






— *^ r ' / 




A "V. 


~J K / 




- *. \ 



■ r. ~— _ , . 




plates f- t", held down on disk F by. two 
other terminals, c 4 , c 4 , making contact 
them as shown at y. I .. . 

The action of the switch is shown in Fig. 
1. Connect terminal e* to the carbon of a 
battery, and cr to the zinc. Then, if you 
turn handle K to the right, so that the 
strips, e 1 and e 2 touch b l and b\ respective- 
ly, terminal c* will show -f- and <r — elec- 
tricity; vice versa, if you turn the handle 
to the left so that e E and *r touch b-* and b 1 , 
respectively, terminal c" will show — and 
- electricity. 

The switch is easy to make and or" 
neat appearance. The wooden parts could 
be made of any insulating material, as fiber, 
for instance.— Contributed by Arthur Schulz, 
1111 Rut!edge St., Madison, " - 



REVERSING A SMALL MOTOR 



All that is necessary for reversing the 
motor is a pole-changing switch. Connect 
the two middle posts of the switch with 
each other and the two outside posts with 
each other. Then connect one of the outside 
posts of the switch to one brush of the 
motor and one middle post to the other 
brush. 

Connect one bar of the switch to one end 
of the field coil and the other bar to one pole 
of the battery and connect the other pole of 
the battery to the other field coil. To re- 



Suitable for Students' Use 

terminals, or binding posts. e ! . c 2 , and a 
common screw, d. Post c- is connected to 
d by means of an insulated wire, making 
them carry the same kind of current (-5- in 
the sketch). 

About the center piece. H, moves a disk, 
held down by another dist F (Fig. 2). 
which is fastened through the center piece 
to the wooden base. A, by means of tw 
wood screws. On the disk, O, are two brass 
strips, (r and e 1 . so arranged that, when 
handle K is turned to one side, their one 
end just slips under the strips b 1 , b\ or 
r—rectively. making contact with 
them, as shown in Fig. 2 at L. while their 
other ends siide in two half circular brass 





. ^ __ 


1 




^■> K - , ' 


■- £=- - 


-:dTU 




'^;;, a ; . 




/ ^^^^ - 


~ 11- . 







itch. 



Reverse for a S 



verse the motor, simply change 

Referring to the illustration, the letters in- 
dicate as follows: FF. field of motor: BB, 
brushes of motor: AA, bars of pole- chang- 
ing switch; DD. center points of switch; 
CC. outside points of switch.— Contributed 
by Leonard E. Parker. Plymouth, Ind. 



POPULAR MECHANICS 



AN INGENIOUS ELECTRIC LOCK 
FOR A SLIDING DOOR 



The apparatus shown In Fig. 1 not only 
unlocks, inn ..pens the door, also, by sim- 
ply pressing the key In tin' keyhole. 

In rigging it to a sliding <loor, the mate- 
rials required are: Three flat pulleys, an 
old electric bell or buzzer, about 25 ft. of 



the key. for the drcull cannot be , loted with 
an ordinary nail or wire. B, I 
catch B, Pig. 1, enlarged; 0, Fig. 2, li the 
cat throngb which the rope runs. 11. i .. 

is an elastic that snaps the catch back into 
place, and at G the wire-; run outside to 
the keyhole. 

Tins arrangement is very convenient whew 
one is carrying something In one hand and 
can only use the other, doting the door 




Electric Lock for Sliding Door 



clothesline rope and some Xo. 18 wire. The 
wooden catch, A (Fig. l),must be about 1 in. 
thick and 8 in. long; B should be of the same 
wood, 10 in. long, with the pivot 2 in. from 
the lower end. The wooden block, C, which 
is held by catch B, can be made of a 2-in. 
piece of broomstick. Drill a hole through 
the center of this block for the rope to pass 
through, and fasten it to the rope with a 
little tire tape. 

When all this is set up, as shown in Fig, 
1, make a key and keyhole. A *4-in. bolt 
or a large nail sharpened to a point, as at 
F, Fig. 3, will serve for the key. To provide 
the keyhole, saw a piece of wood,. I, 1 in. 
thick by 3 in. square, and bore a hole to fit 
the key in the center. Make a somewhat 
larger block (E ; Fig. 3) of thin wood with 
a %-in. hole in its center. On one side of 
this block tack a piece of tin (K, Fig. 3) 
directly over the hole. Screw the two blocks 
together, being careful to bring the holes 

Opposite each other. Then, when the point 
of the key touches the tin. and the larger 
part (F, Fig. 3) strikes the benl wire. ]., ;i 

circuit is completed; the buzzer knocks catch 

A (Fig. 1>. which rises at the opposite end 
and allows catch B t" fly forward and re- 
lease the piece of broomstick, <". The weight, 

D, then falls and jerks np the hook-lock, M. 

which unlocks the door, and the heavier 

weight, \. Immediately opens jt. 

Thus with a BWitcb as in Fig. 3. the door 

can only be opened by the person who has 



winds the apparatus up again.— Contributed 
by E. H. Klipstein, 116 Prospect Bt, I i-t 
Orange, New Jersey. 



ANOTHER ELECTRIC LOCK 



The details of the construction of an elec- 
trically operated lock are shown in the il- 
lustration. When the door is closed and the 

bolt, a. pushed into position it automatically 



2^ 




Simple BtoCtrk Lock 

locks lo unlock, push the button, D, which 
act will cause the electro-magnet to raise 

the latch. ( '. When the holt may be drawn 

and the door opened Contributed by a D. 
Zimmerman, Doody, ill. 



POPULAR MECHANICS 




YOUNGEST RAILROAD PRESIDENT IN THE WORLD 



The youngest railroad president in the 
world is Carleton Kinney, nine years old. of- 
ficial bead of the Venice Railroad Co.. which 
operates in Venice, Calif., twelve miles from 
Los Angeles. Carleton has charge of the 
general management and operation of the 
line, and his brother Innes Kinney. 13 years 
of age, is chief engineer. The road is two 
miles long, laid with light T-rail to 18-in. 
gage. There are two locomotives built at 
Los Angeles, after the model of the big stan- 
dards They are oil burners, carrying 160 
pounds of steam; weight, 6 tons each; 
diameter of cylinders, 5 in.; stroke, 7 in.; 
6 drivers, 20 in. diameter; height to top of 



stack. 5T 1 - in.: maximum speed, 25 miles 
per hour. Each engine will draw 5 cars, 
which, loaded, weigh a total of 16 tuns. 
Fuel consumption % gal. of oil per mile. 

The cars are 20 ft. long, steel frames, open 
type, reversible seats, accommodate 12 pas- 
sengers. A round trip is made in 3 minutes: 
fare 5 cents. The father of the boys built 
the line and turned it over to them. 




HOW TO MAKE A GALVANOSCOPE 

A galvanoscope for detecting small cur- 
rents of electricity can be made from a 
coil of wire. A; a glass tube. B. full of 
water: a core, C; and a base. D. with bind- 
ing posts as shown. The core C, which is 
made of iron 
and cork is a 
trifle lighter 
than the wa- 
ter it displac- 
es and will 
therefore re- 
main in the 
top of the 
tube normal- 
ly ; but a s 
soon as a cur- 
rent of elec- 
tricity 




Pres. Carleton Kinney rat rights; Chief Engineer 
Innes Kinney (left) 



through the coil, the core is drawn down 
out of sight. The current required is very 
small as the core is so nearly balanced 
that the least attraction will cause it to 
sink. 

The glass tube may be a test rube as 



POPULAR MECHANICS 



shown in Ficr. 2. or an empty developer 
tube. If one baa neither ;i teal tube nor de- 
veloper tube. :m empty pill bottle may be 
used. The washers at the ends of the 
coil can be made of fibre, hard rubber, 

or w I: or can lie taken from an old 

magnet The base may be made of wood 
or any other Insulating material and 
should have four short legs on the bottom. 
Make tlu> coll of Bingle covered wire about 
od conned ends to binding posts 
as shown In Fig 2. 

The core is made by pushing a small 
nail through a piece of cork. It should 
be made so that it will rise slowly when 
placed under 
water Rome 
filing may he 
necessary to 
get the weight 
just right, but 
it should be 
rememb e r e d 
that the buoy- 
ancy of the 
core can be 
adjusted, af- 
ter the parts 
are assembled, 
b y pressing 
the cork in the bottom of the test tube. 
This causes compression in the water space 
and specially of the upper cork, reducing 
its displacement and causing it to sink. 
The lower cork is thou slowly withdrawn, 
by twisting, until the core slowly i 
The instrument will then be adjusted ready 
for use. 

Connect the binding posts to a single 
cell of battery— any kind will do as a 
slight current will answer. On enmplet- 
Ing the circuit the core will descend; or 

put in a switch or push button on oi ( 

the battery wires. If the button be con- 
cealed where the operator can reach it, the 
core will obey his command to rise or fall, 
according to his control of the current. 
This is a mysterious looking Instrument the 
core being moved without Visible connection 
to any other part. 




HOW TO MAKE A NEW LANGUAGE 



Any one possessing a phonograph can try 
a very Interesting and amusing experiment 
without going to any expense. Remove the 

belt and replace with :i longer one. which 

can be made of narrow braid or a numbei 

of strands of yarn The new belt should 



be long enough to allow crossing it. thus 
ie\ ersing the machine, l in- 
sound .»n the record and changes II to rack- 
an extent tii.it very few words can be rec- 
ognised. 



MINIATURE ELECTRIC LIGHTING 



Producing electric light by means of small 
bulbs that give from one-half to six candle 
power, and a suitable Bource of power. is 
something that will interest the average 
American boy. 







If 


^ Y Y Y Y Y 


^jt. Bulbs in t>jses 


Fig. 1 



These circular bulbs range from one-quar- 
ter to two inches in diameter, and CO 
cents each complete with base. They are 
commonly known as miniature battery 
bulbs, since a battery is the most popular 
source of power. The one-half candle power 
bulbs are usually 2% volts and take one- 
quarter ampere of current, it requires about 
three medium dry cells to operate it. How- 
ever, there is now upon the market a bat- 
ten consisting of three small dry cells con- 
nected in series, put up In a neat case with 
two binding posts, which sells for 25 cents. 
This Is more economical than dry cell 
It gives about 4 volts ai i. it 

will run as large a lamp as 3'j volts. 

candle power, for some time very sal 
torily. More than one lamp can be run by 
Connecting the bulbs In parallel, as indicated 

by i"iir. 1, which shows the special battery 
with 3 dry cells In the case, and the two 

binding posts for connection with the bulbs. 
In this case it is also advisable to connect 
several batteries in parall< to in- 

crease the current, but maintain the 
stant voltage. Thus, the Individual cells 

are in multiple series, i. e., multip'. 

Bertea of three, By keeping in mind the 

ampere output Of the battery and ratiiiL' 

of the land', one can regulate the batteries 
mired. It must be d, In 

this connection, that any battery which is 
drawn upon for half of its output will last 
approximately tin-. ■ long, as if 

drawn upon for its total output. Thus, in 

any system of lamps it is economical lo 



POPULAR MECHANICS 



25 



powder can, or a syrup can with a tube 
soldered to it. and is connected to the en- 
gine by a piece of rubber tubing. The heat 
from a small gas stove will furnish steam 
fast enough to run the engine very fast. 
This engine was built by W. G. Schuh and 
A. J. Eustice, of Cuba. Wis. 

SMALL ELECTRICAL HYDROGEN 
GENERATOR 



A small hydrogen generator may be made 
from a fruit jar, A (see sketch), with two 
tubes, B C, soldered in the top. The plates, 
E, can be made of tin or galvanized iron, 




Hydrogen Generator 

and should be separated about % in. by 
small pieces of wood. One of these plates 
is connected to metal top, and the wire from 
the other passes through the tube, B, which 
is filled with melted rosin or wax, to make 
it airtight. This wire connects to one 
side of a battery of two cells, the other wire 
being soldered to the metal top of the jar, 
as shown. The jar is partly filled with a 
very dilute solution of sulphuric acid, about 
20 parts of water to 1 of acid. 

When the current of electricity passes 
between the plates, E, hydrogen gas is 
generated, which rises and passes through 
the rubber hose, D, into the receiver, G. 
This is a wide-mouth bottle, which is filled 
with water and inverted over a pan of 
water, F. The gas bubbling up displaces the 
water and fills the bottle. 

If the receiver is removed when half full 
of gas, the remaining space will be filled 
with air, which will mix with the gas and 
form an explosive mixture. If a lighted 
match is then held near the mouth of the 
bottle a sharp report will be heard. 

If the bottle is fitted with a cork contain- 
ing two wires nearly touching, and the ap- 
paratus connected with an induction coil, 
in such a manner that a spark will be 
produced inside the bottle, the explosion 



will blow out the cork or possibly break 
the bottle. Caution should be used to avoid 
being struck by pieces of flying glass if this 
experiment is tried, and under no condition 
should a lighted match or spark be brought 
near the end of the rubber hose, D, as the 
presence of a little air in the generator will 
make an explosive mixture which would 
probably break the jar. 



HOW TO MAKE A CHEAP BRACKET 
SAW 



For the frame use %-in. round iron, 
bending it as shown in the diagram and 
filing a knob on each end, at opposite sides 
to each other, on which to hook the blade. 

For the blade an old talking machine 
spring or a clock spring will do 
nicely. Heat the spring enough to 
take some of the temper out of it, in 
order to drill the holes in the ends, as 




Hack Saw Frame and Blade 

shown, and file in the teeth. Make the 
blade 12 in. long, with ten teeth to the inch. 
A and B show how the blade fits on the 
frame. — Contributed by Willard J. Hays, 
Summitville, Ohio. 

WHY GRAVITY BATTERIES FAIL TO 
WORK 

Many amateur electricians and some pro- 
fessionals have had considerable trouble 
with gravity batteries. They follow direc- 
tions carefully and then fail to get good re- 
sults. The usual trouble is not with the 
battery itself, but with the circuit. A 
gravity battery is suitable only for a cir- 
cuit which is normally closed. It is there- 
fore undesirable for electric bells, induction 
coils and all other open circuit apparatus. 
The circuit should also have a high resist- 
ance. This makes it impractical for run- 
ning fan motors, as the motor would have 
to be wound with fine wire and it would 



26 



POPULAR MECHANICS 



then require a large number of batteries to 
give a sufficiently high voltage. 

The directions for setting up a gravity 
battery are as follows: Use about 3% lbs. 
of blue stone or enough to cover the copper 
element one inch. Pour in water sufficient 
to cover the zinc one-half inch. Short-cir- 
cuit for three hours and the battery is ready 
for use. If desired for use immediately do 
not short-circuit, but add 5 or 6 oz. of zinc 
sulphate. 

Keep the dividing line between the blue 




Setting up a Gravity Battery 

and white liquids about one-half inch below 
the bottom of the zinc. If too low syphon 
off some of the white liquid and add the 
same amount of water, but do not agitate or 
mix the two solutions. This type of bat- 
tery will give about .9 of a volt and should 
be used on a circuit of about 100 milli- 
amperes. 

CALLERS' APPROACH ALARM 



This alarm rings so that callers approach- 
ing the door may be seen before they ring 
the bell and one can exercise his pleasure 
about admitting them — as in the case of 
agents or beggars; it may not be desirable 
to see them. 

If one has a wooden walk the alarm is 
easy to fix up. Take up about 5 ft. of the 
walk and nail it together so as to make a 
trap door that will work easily. Place a 
small spring under one end to hold it up 
about !, in. i \. Pig. L'l. Nail a strip of 
tin along the under Bide of the trap near 
the spring and fasten another strip on the 
baseboard, so that they will not touch, Bare 
when a weight is on the trap Conned up 



an electric bell, putting the batteries ami 
bell anywhere desired, and using rubber- 
covered wire outside the house, and the 
alarm is complete. 




Alarm Rings When Caller Approaches 

When any person approaching the house 
steps on the trap the bell will ring and 
those in the house can see who it i 
fore the door bell rings. — Contributed by 
R. S. Jackson. Minneapolis, Minn. 

AN OPTICAL TOP 



One of the latest optical delusions, and 
one not easy to explain, is Benham's color 
top. Cut out the black and white disc 
shown in the figure, and paste on a piece of 
stiff cardboard. Trim the edges of the card' 
board to match the shape of the disc, and 
make a pin hole in the center. Cut the 
pin in half and push through from the 
under side until the head of the pin touches 
the cardboard. Spin slowly in a Strong 
light and some of the lines will appear 
colored. The colors appear different to dif- 
ferent people, and are changed by reversing 
the rotation. 




An Optical Top 



POPULAR MECHANICS 



D1RECT=C0NNECTED REVERSE 
FOR SMALL MOTORS. 



ALARM CLOCK TO PULL UP FUR= 
NACE DRAFT 



A simple reverse for small motors can be 
attached directly to the motor as shown in 
Fig. 1. Fig. 2 shows the construction of the 
reverse block: A is a strip of walnut % in. 
square and 3 i in. thick with strip of brass 
or copper (BB) attached as shown. Holes 
(CC) are drilled for the wire connections 
and they must be flush with the surface of 
the block. A hole for a *&-in. screw is bored 
in the block. In Fig. 1. D is a thin strip 
of walnut or other dense hard wood fitted 







4-fi 


ra n Jsm\ 






Hr 


, rV 


F«>1 \^ 


/ 








Fig- a 


1 _S °2 — J— 6 

1 o'»™" — *-R 
c> 



Direct=Connected Reverse. 

to the binding-posts of the brush holders, to 
receive the screw in the center. 

Before putting the reverse block on the 
motor, remove all the connections between 
the lower binding posts and the brush hold- 
ers and connect both ends of the field coil 
to the lower posts. Bend the strips, BB (Fig. 
2), to the proper position to make a wip- 
ing contact with the nuts holding the strip 
of wood ~D, Fig. 1. Put the screw in tight 
enough to make the block turn a little hard. 
Connect as shown in the illustration. To 
reverse, turn the block so the strips change 
connections and the motor will do the rest. 
—Contributed by Joseph B. Keil, Marion, 
Ohio.. 



A stout cord, A, is attached to the draft, 
B, of the furnace, run through a pulley, C, 
in the ceiling and has a window weight, D, 
attached at the other end. A small stick 




Automatic Time Draft=Opener. 

is put through a loop in the cord at about 
the level of the table top on which the 
alarm clock, F, stands. The other end of 
stick, E, is placed under the key, G, of the 
alarm clock. When the alarm rings in the 
early morning, the key turns, the stick 
falls away, releasing the weight, which 
pulls the draft open. — Contributed by Ed- 
ward Whitney, 18 Gorham St., Madison, Wis. 

HANDY ELECTRIC ALARM 



An electric alarm which may be turned 
off from the bed without one's arising and 
also having a light which may be turned 





^fH 


Q 


¥ " 


-A 

3 


l 




Jfnrt 





Handy Electric Alarm. 



POPULAR MECHANICS 



on and off from the bed, so one can see the 
time, is the device of H. E. Redmond, of 
Burlington, Wis. 

The alarm clock rests on a shelf. A, which 
has a piece of metal, B, fastened in such 
a position that the metal rod, C, soldered 
to the alarm winder, will complete the cir- 
cuit and ring the bell. The two-point 
switch, D, is closed normally at E, but may 
be closed at F any time desired, thus turn- 
ing on the small incandescent light, G, 
which illuminates the face of the clock. 
When the alarm goes off, the bell will con- 
tinue to ring until the switch is opened. 



EASILY MADE WIRELESS COHERER 



CONTROLLER FOR A SMALL MOTOR 



A good wireless coherer may be made with 
very little expense, the only materials neces- 
sary being a glass tube, two corks, a mag- 
netized needle and a quantity of iron and 
silver filings. Push a piece of wire through 
one cork and place in the bottom of the 
tube, as shown in the sketch. 

Pour in the filings and insert the top cork 
with the needle pushed through from above. 
The point of the needle should barely touch 
the filings and by slightly agitating the tube 
the iron filings will separate from the silver 
and cling to the magnetized needle, as 
shown. 

In operation the device must stand on 
end and should be connected in the circuit, 



P ^J-cork 



— Magnetized 
a Needle 



-Glass tube 



h' 



N=3> 



Iron Filings 
"^jf-QSHver Filings 
\N\re 
-Cork 



Details of Coherer 

as shown in the sketch. When the elec- 
trical waves strike the needle the conduc- 
tivity of the filings is established and a 
click is heard in the receiver. — Contributed 
3y Carl Formhals, Garfield. 111. 



An easy wray of making a controlling and 
reversing device for small motors Is as fol- 
lows: 

Cut a piece «'i" wood (.\) about •; In. by 

-»'_• and ' i in. thick, ami another p I 
6 In. by l In. and ', In. thick. Drive ■ 
nail through this near the center for a pivot 
(C). To the under side of one end nail 




Reverse for Motor 

a copper brush (D) to extend <>ut about an 

inch. On the upper side at the same end, 
nail another brush (E) so that it projects 
at both sides and is bent down to the level 
of the end brush. Then on the board put 
a semi-circle of brass-headed tacks as shown 
at F, leaving a small space at the middle 
and placing five tacks on either side, so that 
the end brush will come in contact with 
each one. Connect these tacks on the tinder 
side of the board with coils of German sil- 
ver wire, using aboul 8 In. of wire to each 
coil. Fix these by soldering or bending 
over the ends of the tacks. Then nail two 
strips of copper ((it in such position that 
the side brush will remain on the one as 
long as the end brush remains on the tacks 

on that side. 

Put sides about 1% in. high around this 
apparatus, raising the hoard a little from 
the bottom to allow room for the coil. \ 
lid may be added if desire. 1. Conned up as 

shown. Contributed by < has. n. Boyd, 
Phila., Pa. 



Wh.n tilling nail holes in yellow pine use 
beeswax instead of putty, as it matches the 
color well. 



The Boston & Maine Railway is trying 
peat fml in one of its locomotives and. it is 
said, with good results. Maine lias vast 
peat bogs. 



POPULAR MECHANICS 



HOW TO MAKE AN AQUARIUM 



In making an aquarium, the first thing to 
decide on is the size. It is well not to at- 
tempt building a very large one, as the 
difficulties increase with the size. An aqua- 
rium about 12 in. by 12 in. by 20 in. is a 
very good size and is inexpensive to build. 

First buy one length of %-in. by &-in. 
angle iron for the frame, F, Fig. 1. This 
can be obtained at any steel shop and should 
cost about 20 cents. All the horizontal 
pieces, B, should be beveled 45° at the ends 
and drilled for i'\,-in. stove bolts. The bev- 
eling may be done by roughing out with a 
hacksaw and finishing with a file. After 
all the pieces are cut and beveled they should 
be drilled at the ends for the ft-in. stove 
bolts, C. Drill all the horizontal pieces, B, 
first and then mark the holes on the up- 
right pieces. A, through the holes already 
drilled, thus making all the holes coincide. 
Mark the ends of each piece with a figure or 
letter, so that when they are assembled, the 
same ends will come together again. The 
upright pieces, A, should be countersunk as 
shown in the detail, and then the frame is 
ready to assemble. 

After the frame has been assembled take 



: 


jin 
JL/ 




JJIb ~~t 


3 

^^-B 


FV E 


,/D Af ~~""~"~"" ' 


t=^ F,g. . 





Details of Aquarium Frame 

it to a glazier and have a bottom made of 
sky-light glass, and sides and ends of double 
thick window glass. The bottom glass 
should be a good fit, but the sides and ends 
should be made slightly shorter to allow the 
cement, E, to form a dovetail joint as shown. 
When the glass is put in the frame a space, 
D, will be found between the glass and the 
horizontal pieces, B, of the frame. If this 
were allowed to remain the pressure of the 
water would spring the glass and cause a 
leak at E, so it is filled up with plaster of 
paris. 



The cement, E, is made as follows: Take 
1 gill of plaster of paris, 1 gill of litharge, 
1 gill of fine white sand, and 1-3 of a gill of 
finely powdered rosin. Aix well and add 




Aquarium Finished 

boiled linseed oil and turpentine until as 
thick as putty. Let the cement dry three or 
four days before putting any water in the 
aquarium. 

In choosing stock for the aquarium it 
should be remembered that a sufficient quan- 
tity of vegetable life is required to furnish 
oxygen for the fish. In a well balanced 
aquarium the water requires renewal only 
two or three times a year. It is well to have 
an excess of plants and a number of snails 
as the snails will devour all the decaying 
vegetable matter which would otherwise 
poison the water and kill the fish. 

If desired, a centerpiece (A, Fig. 2) can 
be made of colored stones held together by 
cement, and an inverted jar can be sup- 
ported in the position shown at B. If the 
mouth of the jar is below the surface of the 
water it will stay filled and allow the fish 
to swim up inside as shown. Some washed 
pebbles or gravel should be placed on the 
bottom, and if desired, a few Chinese lilies 
or other plants m&jjc_be placed on the center- 
piece, v. 



POPl'I, A R M BC HANICS 



HOW TO MAKE A CANNON 



A cannon, like the one in the cut, can be 
made from a piece of 1-in. hydraulic pipe, 
A, with a steel sleeve, B, and a long thread 




Toy Cannon 



plug, C. Be sure to get hydraulic pipe, or 
double extra heavy, as it is sometimes called, 
as common gas pipe is entirely too light for 
this purpose. Don't have the pipe too long, 
or the cannon will not make as much noise. 
Seven or eight inches is about the right 
length for a 1-in. bore. Screw the plug and 
pipe up tightly and then drill a ,V,-in. fuse 
hole at D. 

If desired the cannon may be mounted on 
a block of wood, F, by means of a U-bolt or 
large staple, E. — Contributed by Carson 
Birkhead. Moorhead, .Miss. 



EASY EXPERIMENTS WITH ELEC= 
TRIC LIGHT CIRCUIT 



An electric light circuit will be found 
much less expensive than batteries for per- 
forming electrical experiments. The sketch 
shows how a small arc light ami motor can 
be connected to the light socket, a. The 
light is removed and a plug with wire con- 
nections is put in its place. One wire runs 
to the Bwitch, B, and the other connects 
with the water rheostat, which is used for 
reducing the current. 



ft 


-Jb/\-~<iY 


A 


B 


1. 


[□Eg 

f3S 


— -it— - 




| 


. ) — u — \ 


C 









\ tin can, C i Oiled Dearly to the top 

With salt water ;i ml a metal rod, I >. is ; 

through a piece of u | 

of tiie can. When tin- metal !■■ 
the i iirrenl Increases ami as it is withdrawn 
the current in tins « 

desired amount of current can be obtained. 
By connecting the motor, E, ami t>. 

light, !•'. a- BhOWn, either one may Ik> op- 

I by turning 
spending point The an- light can he . 
made by fastening two electric-light carbons 

in a wooden frame like thai shown. To 
start the light, turn the current on strong 
and bring the points of the carboi 
gether; then separate slightly by twisting 
the upper carbon ami at th< 
drawing i* through the hole. 



PECULIAR PROPERTIES OF ICE 



Arc Light Motor and Water Rheostat 



Of all the boys who make snowballs prob- 
ably few know what occurs during the proc- 
ess. T'nder ordinary conditions water turns 
to Ice when the temperature falls to 32°. 
but when in motion, or under ; 
much lower temper- 
atures are required 
to make it a solid. 
In the same way. ice 
which is somewhat 

below the freezing 

point can he made 

liquid by applying 
pressure, ami will 
remain liquid until 
the pressure is re- 
moved, when it will 
again return to its 
original state. Bnow 
being simply finely 
divided ice. becomes 

liquid in places 

when , ompn 

the hands, and when 
the pn 

moved the liquid 
portions solidify and 
unite all the par- 

in one m .old 

weather it is almost Impossible to make a 
snowball, because a greater amount of ■ 
sure is then required to ma! ■ 
liquid. 

This process of melting ami freezing un- 
der different pressures ami a constant tem- 

perature can be better illustrated by the 

ment shown in Fits 1. L' ami 
block of ice, A, Fig. 1, is supported at each 




POPULAR MECHANICS 



end by boxes BB, and a weight, W, is hung 
on a wire loop which passes around the ice 
as shown. The pressure of the wire will 
then melt the ice and allow the wire to 
sink down through the ice as shown in Fig. 
2. The wire will continue to cut its way 
through the ice until it passes all the way 
through the piece, as shown in Fig. 3. This 
experiment not only illustrates how ice melts 
under pressure, but also how it solidifies 
when the pressure is removed, for the block 
will still be left in one piece after the wire 
has passed through. 

Another peculiar property of ice is its 
tendency to flow. It may seem strange that 
ice should flow like water, but the glaciers 
of Switzerland and other countries are lit- 
erally rivers of ice. The snow which accu- 
mulates on the mountains in vast quanti- 
ties is turned to ice as a result of the enor- 
mous pressure caused by its own weight, 
and flows through the natural channels it 
has made in the rock until it reaches the 
valley below. In flowing through these chan- 
nels it frequently passes around bends, and 
when two branches come together the bodies 
of ice unite the same as water would under 
the same conditions. The rate of flow is 
often very slow; sometimes only one or two 
feet a day, but no matter how slow the mo- 
tion may be the large body of ice has to 
bend in moving. 

This property of ice is hard to illustrate 
with the substance itself, but may be clearly 
shown by sealing-wax, which resembles ice 
in this respect. Any attempt to bend a 
piece of cold sealing-wax with the hands 
results in breaking it, but by placing it be- 
tween books as shown on page 8, or support- 
ing it in some similar way it will grad- 
ually change from the original shape A, and 
assume the shape shown at B. 

SPIT TURNED BY WATER POWER 



Many of the Bulgarian peasants do their 
cooking in the open air over bonfires. The 
American Artisan describes a labor-saving 
machine in use which enables the cook to 




the spit to which the meat is fastened is 
constantly turned by means of a slowly 
moving water wheel. Some of our readers 
may wish to try the scheme when camping 
out. The success depends upon a slow cur- 
rent, for a fast turning wheel will burn the 
meat. 



COMBINED DOOR BELL AND ELEC= 
TRIC ALARM 



For a Summer Camp 

go away and leave meat roasting for an 
hour at a time. The illustration shows how 



This device consists of a battery and bell 
connection to an alarm clock and also acts 
as a door bell, the whole being mounted 
on a board 18 in. long and 12 in. wide. 

Referring to the sketch, the letters indi- 
cate as follows: 
A, bell; B, bat- 
tery; C, switch; 
D, V-s h a p e d 
copper strip; E, 
copper lever 
with 1-in. flange 
turned o n one 
side; whole 
length, 4 in.; F, 
spring to throw 
lever, E, down 
i n V-s h a p e d 
piece to make 
connection; G, 
lever to hold out 
E when device 
is used as a door 
bell; dotted 
lines, H, go, one 
from bell, A, 
and one from 
battery, B, to 
the door; I, 
shelf for clock. 

See that the ring in the alarm key of the 
cIock works easily, so that when it is 
square across the clock it will drop down. 
Fasten a piece of copper about 1 in. long 
to key, then wind the alarm just enough so 
that the key stands straight up and down. 
Place the clock on the shelf and the key 
under the flange of lever, E. Pull lever, G, 
down out of the way and close the lever on 
the switch. The alarm key will turn and 
drop down, letting lever, E, drop into the 
V-shaped piece, D, and make connection. 

For the door bell connection close lever 
on switch, C, and put G up so that D and 
E do not come in contact. If any one is ill 
and you do not want the bell to ring, open 
switch, C. 

The wiring for this device may all be on 




Door Bell and Alarm Combined 



32 



POPULAR MECHANICS 



the back of the board. The switch and 
levers are fastened with small screw bolts, 
which allows wiring at tin- back. B 
spools in half and fasten the halves to the 
four corners of the board at the hack and 
the apparatus can be put up where one likes. 

HOW TO MAKE A TELEGRAPH KEY 
AND SOUNDER 



The soiinder, Fig. 1. is made from an old 
electric bell magnet. D, fastened to a 
wooden base. The lever, A. can be made 




magnet. The binding poet 
from old drj 
it,.- two p Irea from the d 
in grooves cat In th< 
The 

(if w< 

which are n milar 

key is made of br 
wood knob 

BWiti I 

can be i It I u 

taken from a Bmal 

binding posts an 

ami are coi K by 

wires run In | 



HOW TO MAKE \ u \WM RHEO- 
STA1 



SOUNDER- A. bl C, ■Oft Iron; DD, 

rolls around with No. 20 wire; B, nail soldi 
FF, btndli g posts; ii. spring. 

of brass and the armature, C, is made of 
Iron. The pivot, E, is made from a wire 
nail and is soldered to A. It should be filed 
to a point at each end so as to move freely 
in the bearings, B, which are pieces of hard 
wood. 

The spring. H, is fastened at each end by 
pins, bent as shown, and should not be too 
strong or the magnet will be unable to. move 
the armature. The stop, K, is a wire nail 
driven deep enough in the base to leave 
in. between the armature and the 




- :: 






A water rheo l y fitting 

a brass tube with a cork, through which 
a piece of win 
may be an old bi- 
cycle hand pump, 
A (see sketch), 
filled with P 
Poshing the wire. 
B, down Into 

water Ut-gulatinir 

the surface in con- 
tact, and thus de- 
creases the 

■1 hsfpeiani 
paratus o f this c«l 
kind is suitable 

eurrenl from an ^ : 

induction c o i l. of 

wh<n the coll li M ,, t ,, r 
not provided with 

a regulator, i n d 
by using ■ ; 
of pipe Instead of 

LH he 

When the pi] • 
or CO] ; : the 

wire, in ord< I 

will 

John 

: 



nail ; 1111. binding posts. 



To 
ammonia 01 



POPULAR MECHANICS 



ALARM CLOCK CHICKEN FEEDER 



An automatic hen feeder, which will dis- 
charge the necessary amount of corn or 
other feed at any 
desired time, can he 
made by using an 
alarm clock as 
shown in the sketch. 
A small wire trig- 
ger rests on the 
winding key and 
supports the swing- 
ing bottom of the 
food hopper by 
means of a piece of 
string which con- 
nects the two. When 
the alarm goes off 
the trigger drops 
and allows the door 
to open, thus dis- 
charging the con- 
tents of the hopper. 

After the device has been in operation for 
some time the hens will run to the feeder 
whenever the bell rings. — Contributed by Dr. 
H. A. Dobson, Washington, D. C. 

HOW TO DISCHARGE A TOY CAN= 
NON BY ELECTRICITY 



be fired from a distance in this way, and 
as there is no danger of any spark remain- 
ing after the current is shut off, it is safer 




A device for discharging a toy cannon by 
electricity can be easily made by using three 
or four dry batteries, a switch and a small 
induction coil capable of giving an %-in. 
spark. Fasten a piece of wood, A, to the 
cannon, by means of machine screws or, 
if there are no trunnions on the cannon, the 
wood can be made in the shape of a ring 
and slipped on over the muzzle. The fuse 
hole of the cannon is counterbored as shown 
and a small hole is drilled at one side to 
receive a small piece of copper wire, E. The 
wood screw, C, nearly touches E and is con- 
nected to one binding-post of the induction 
coil. The other binding-post is connected 
with the wood screw, D, which conducts 
the current into the cannon, and also holds 
the pieces of wood, A and B, in position. 

When the cannon is loaded, a small quan- 
tity of powder is placed in the counterbore, 
and the spark between C and E ignites this 
and discharges the cannon. A cannon may 




Electrical Attachment for Discharging Toy Cannon 

than the ordinary cannon which is fired 
by means of a fuse. — Contributed by Henry 
Peck, Big Rapids, Mich. 



EXPERIMENT WITH TWO=FOOT 
RULE AND HAMMER 



An example of unstable equilibrium is 
shown in the accompanying sketch. All 
that is needed is a two-foot rule, a hammer, 
a piece of string, and a table or bench. The 
experiment works best with a hammer hav- 
ing a light handle and a very heavy head. 

Tie the ends of the string together, form- 




Equilibrium Experiment With Hammer and Rule 

ing a loop, and pass around the hammer 
handle and rule. Then place the apparatus 
on the edge of the table, where it will re- 
main suspended as shown in the sketch. — 
Contributed by Geo. P. Schmidt, Culebra, 
Porto Rico, W. I. 



POPULAR MECHANICS 

HOW TO MAKE A LATHE 



a small speed-lathe, suitable for turning 

wood <>r small metal articles, can be easily 
made at very little expense. A lathe of 
kind is shown in the cut i Fig. 1 I. 
where \ i> the bead stuck, m the bed and C 
the tail -tm k. | run my lathe hy power, 
USlng an electric motor ami counter shaft. 
Init it could 1"' run hy foot power if de- 
slred. A large cone pulley would then be 
required, hut this could )»■ made in the 
same manner a- tin- small one, which will 
ribed later. 

Tin' hid of tin- machine is made of wood 



The notches for this purpose may be 
aboul U in. pitch and y H in. deep. Place 
pieces of wood against the ends of the bear- 
ing as shown at A and B, Fig. 4, and drill 
a hole in the top of the bearing as shown in 
Fig. 4. 

rhe bearing is then ready to be poured. 
Heal the babbitt well hut not hot enough 
to hum it ami it is well to have the shaft 
hot, too, so that the babbitt will not be 
Chilled when it strikes the shaft. If the 
shaft is thoroughly chalked or smoked the 
babbitt will not stick to it. After pouring, 




Assembled Lathe Bed and Bearing; Details 



as shown in F*ig8. L' ami ::, hard w I beiiiK 

preferable for this purpose. Fig. - shows 

an end view of the assembled bed ami Fie 

:: shows how tl mis are cut out to receive 

the gide pi< 

The head stock. Pig. <;. is fastened to the 

bed by means of carriage holts, a. which 

pass through a piece of wood. I'., on the 
under side of the bed. The shaft is made 
of '• i -in. steel tubing about 's-in. tnick, and 
runs in babbitt hearings, one of which is 
shown in Pig. .". 

To make these hearings, cut a square hole 
in the wood as shown, making half of the 
square in each half of the hearing. Sepa- 
rate the two halves of the bearing slightly 
hy placing a piece of cardboard on each 
Bide, just touching the shaft. The edges 
which touch the shaft should he notched like 
the teeth of a saw, so as to allow the bab- 
bitt to run into the lower half of the bearing. 



remove the shaft and split the bearing with 
a round wooden tapered pin. If the bear- 
ing has been properly made, it will split 
along the line of the notched cardboard 
where the section of the metal is the small- 
est. Then drill a hole in the top as shown 
at A, Fig. 5, drilling just deep enough to 
have the point of the drill appear at the 




Head Stock Details 



POPULAR MECHANICS 





w 




= 








.—.. 


_ 


f*£*§' Tsa f\~ l 


A 




if 










- 






K 




\ 


V to) l,» 


<2 






**■> r n #> 1 



are done away with. Closing either key 
will operate both sounders, and as the 
resistance of the sounders is very high the 
batteries do not run down for a long time. 
— Contributed by A. D. Stoddard, Clay Cen- 
ter, Kan. 



HOW TO MAKE AN ELECTROSCOPE 



Details of Tail Stock 

lower side. This cavity acts as an oil cup 
and prevents the bearing from running dry. 

The bolts, B (Fig. 5), are passed through 
holes in the wood and screwed into nuts, 
C, which are let into holes, D, the holes 
afterwards being filled with melted lead. 

This type of bearing will be found very 
satisfactory and might be used to advan- 
tage on other machines. After the bearings 
are completed the cone pulley can be placed 
on the shaft. To make this pulley cut 
three circular pieces of wood to the dimen- 
sions given in Fig. 6 and fasten these to- 
gether with nails and glue. If not per- 
fectly true, they may be turned up after 
assembling, by rigging up a temporary tool 
rest in front of the head stock. 

The tail stock (Fig. 7). is fastened to the 
bed in the same manner as the head stock, 
except that thumb nuts are used on the 
carriage bolts, thus allowing the tail stock 
to be shifted when necessary. The mech- 
anism of the center holder is obtained by 
using a i^-in. pipe, A, and a ^-in. lock nut, 
B, embedded in the wood. 

I found that a wooden tool rest was not 
satisfactory, so I had to buy one. but they 
are inexpensive and much handier than 
home-made tool rests. — Contributed by Don- 
ald Reeves. 6453 Iowa St.. Oak Park, 111. 



SIMPLE OPEN=CIRCUIT TELEGRAPH 
LINE 




An electroscope for detecting electrified 
bodies can be made out of a piece of note 
paper, a cork, and a needle. Push the nee- 
dle in the cork, 
and cut the pa- 
per in the shape 
of a small ar- 
row. Balance the 
arrow on the 
needle as shown 
in the sketch, 
and the instru- 
ment will then 
be complete. 

If a piece of paper is then heated over a 
lamp or stove and rubbed with a piece of 
cloth or a small broom, the arrow will 
turn when the paper is brought near it. — 
Contributed by Wm. W. Grant, 68 Kaye St., 
Halifax. X. S.. Canada. 



TO USE OLD BATTERY ZINCS 



By using the circuit shown in the sketch 
for short-distance telegraph lines, the extra 
switches and wiring found in many circuits 




Simple Telegraph Line 



When the lower half of a battery zinc be- 
comes eaten away the remaining part can 
be used again 
by suspending 
it from a wire 
as shown in 
the cut. Be 
sure and have 
a good connec- 
tion at the 
zinc binding- 
post and cover 
same with 
melted paraf- 
fin. This pre- 
vents corro- 
3 i on which 
would other- 
wise occur 
from the action of the sal ammoniac or other 
chemical. The wire may be held at the top by 
twisting around a piece of wood or by driv- 
ing a peg through the hole in the porce- 
lain insulator. — Contributed by Louis Lau- 
derbach, 174 N. 7th St., Newark, N. J. 




lMHTLAR MECHANICS 




per hour increase for each second. Thus If 
the thread moves one inch, it shows that the 
train is gaining 2 miles an hour each second. 



AN OPTICAL ILLUSION 



The accompanying Illustration shows ■ 

perfectly straighl box* I rule laid over ;i 

number <>f turned bi various 

klthougb tii«' effect la the lllustra- 
mouneed than it was In real- 
ity, it will be noticed that the rule appeari 
in be i" ml but sighting along the rule from 
one and vrlll aho* thai 11 la perfectly 
straight 

The bi riso : t j • i >« ;i r distorted. 

The poi tlom on one iid< of the rule do nol 

:* i • ] >< -: 1 1- to i"- s continuation <>f those on the 

other, but tins can be proved by sighting In 

< iontrlbuted by 

btsman, Chicago. 

♦ • ♦ 

A SIMPLE ACCELEROMETER 



a simple sccelerometer for Indicating the 
: train, was • 
by Mr a P Trotter In a paper read before 
the Junior Institution of ESnginei rs of Oreal 
Britain. The d< of an ordinary 

> ft. rule, a. with s piece of thread tied to 

aown 
In the Bket( n, and sup- 
porting t be small * 
it. which can i"' a button 
or other small object 

The device thus ar 
ranged and phv ed on the 

window sill of thl 

will Indicate the a 
ation and retardation as 
follows: Every '_• In. 
traveled by the thread, 
be benl portion of 
the rule, Indicates an In- 

velocity to the extent of 
1 ft. per second for each 

second. Thus if the 
thread moved _', In. In a direction opposite 
to the movemenl of the train, then the train 
would be Increasing its speed at the rate of 
4 ' .. ft. per second 

If the thread la tied at the 17-in. mark, 
then each half inch will represent the miles 



i 



HOW TO MAKE A QALVANOSCOPE 



To make a galvanoscope for detecting 
small currents of electricity, a magnet, M; 
compass, C; two binding-posts, B B, and a 
base, A, of wood, all as shown in Fig. 1 
(top view), will be required. In Fig. 2 
(side view), S S are supports to the mag- 
net. M. whiih should be ' L .-in. from the 




I or Detecting Small Currents 

C. This galvanoscope will detect 

the weakest current. — Contributed by John 

o 2537 N. Chadwick St., Philadel- 



ANTIDOTE FOR SQUIRREL PEST 



To the owner of a garden in a town where 
squirrels are protected by law, life in the 
summer time is a vexation. First the squir- 
rels dig up the sweet corn and two or three 
replantings are necessary. When the corn 
is within two or three days of being suitable 
for rooking, the squirrels come in droves 
from far and near. They eat all they can 
and carry away the rest. When the corn is 
gone cucumbers, cabbages, etc., share the 
same fate, being partly eaten into. At the 
risk of being arrested for killing the squir- 
rels I have used a small target rifle morning 
and night, but during my absence the 
devastation went on steadily. Last year 
they destroyed my entire corn crop. Traps 
do no good; can't use poison, too dangerous. 
But I have solved the difficulty; it's easy. 

Shake cayenne pepper over the various 
vegetables which are being ruined, and ob- 
serve results. 



POPULAR MECHANICS 



Foundry Work at Home 



Part W=The Equipment 

Many amateur mechanics, who re- 
quire small metal castings in their 
work, would like to make their own 
castings. This can easily be done at 
home without going to any great ex- 
pense and the variety and usefulness 
of the articles produced will make the 
equipment a good 
investment. 

With the easily 
made devices about 
to be described, the 
voung mechanic can 
make his own tele- 
graph keys and 
sounders, battery 
zincs, binding-posts, 
engines, cannons, 
bearings, small ma- 
chinery parts, mod- 
els and miniature 
objects, ornaments 
of various kinds and 
duplicates of all 
these and many 
other interesting and useful articles. 

The first thing to make is a mold- 
ing bench, as shown in Fig. i. It is 
possible to make molds without a 
bench, but it is a mistake to try to 
do this as the sand is sure to get on 
the floor, whence it is soon tracked 
into the house. The bench will also 
make the operation of molding much 
easier and will prove to be a great 
convenience. 

The bench should be made of lum- 
ber about i in. thick and should be 
constructed in the form of a trough, 
as shown. Two cleats. AA, should be 
nailed to the front and back to sup- 
port the cross-boards, BB. which in 
turn support the mold while it is be- 
ing made. The object of using the 
cleats and removable cross-boards 



instead of a stationary shelf is to give 
access to the sand, C. when it is be- 
ing prepared. 

About one or two cubic feet of fine 
molding sand will be required, which 
may be purchased at the nearest foun- 
dry for a small sum. Yellow sand 
will be found a little better for the 
amateur's work than the black sand 
g^enerallv used in most foundries, but 








Fig. l"Convenient Arrangement of Bench and Tools 

if no yellow sand can be obtained the 
black kind will do. If there is no 
foundry near at hand, try using sand 
from other sources, giving preference 
to the finest sand and that which 
clings together in a cake, when com- 
pressed between the hands. Common 
lake or river sand is not suitable for 
the purpose, as it is too coarse and 
will not make a good mold. 

For mixing and preparing the sand 
a small shovel. D. and a sieve. E. will 
be required. If desired the sieve can 
be home-made. Ordinary wire net- 
ting, such as is used in screen doors, 
is about the right mesh and this, nailed 
to replace the bottom of a box, makes 
a very good sieve. 

The rammer. F. is made of wood 
and is wedge-shaped at one end and 



POPULAR MECHANICS 



ilat at the other, as shown. In foun- 
dries each molder generally uses two 
rammers, but for the small work 
which will be described, one will be 
sufficient. An old teaspoon, <i. will 
be found useful in the molding opera- 
tions and may be hung <>n the wall 
or other convenient place when not 

in use. 




II. .mc Made I Usk 

The doth bag, II. which can he 
made of a knitted Stocking, is tilled 
with coal dust, which is used for a 

parting medium in making the molds. 
rake a small lump of soft cal and re- 
duce t" powder by pounding. Screen 

OUt all the coarse pieces and put the re- 
mainder in the bag. A slight -hake 
of the bag Over the mold will then 
cause a cloud of coal dust to fall on 

it. thus preventing the two layers of 

sand from Sticking, hut tin- operation 

will he described more fully in a sub- 
sequent chapter. 

The flask, I. Fig. 1. is shown more 
clearly in Fig. 2. It is made of wood 

and is in two halves, the '"cope" or up- 
per half and the "drag" or lower part. 
1 way to make the tlask is to 
take a box, say 12 in. by 8 in. by 6 
in. high and saw it in half longi- 
tudinally, as shown. If the box is not 
very strong, the corners should he 
braced with triangular wooden strips. 
A A, which should ho nailed in. pre- 
vious to sawing. The wooden strips, 
I'd', are used to hold the sand, which 
would otherwise slide out of the flask 
when the two halves of the mold are 
separated. 



The dowels, CC, are a very impor- 
tant part of the flask as upon them 
depends the matching of the two 
halves of the mold. A wedge-shaped 
piece, CC, is nailed to each end of 
the cope and the lower pieces, DD, 
are then nailed on the drag so that 
they just touch C when the flask is 
closed. The two halves of the flask 
will then occupy exactly the same rel- 
ative position whenever they are put 
together. 

After the tlask is done make two 
hoards as .shown at K. Fig. 1, a little 
larger than the outside of the flask. 
A couple of cleats nailed to each board 
will make it easier to pick up the mold 
when it is on the llo. ir. 

A cast iron glue pot makes a very 

g 1 crucible for melting the metal, 

which can he either aluminum, white 
metal, zinc or any other metal having 
a low melting point. This completes 
the equipment with the exception of 
one or two simple devices which will 
ribed under "molding" in the 
next number. 

Home=/Vlade Pneumatic Lock 



Mount an old bicycle hand-pump, 
A. on the door by means of a metal 
plate, B, having a swinging connec- 
tion at ( '. Fasten the lever, D, to 
the door knob and make a hinge con- 
nection with the pump by means of a 
piece of sheet brass, E, soldered to 
the end of the cylinder. All this ap- 
paratus is on the inside of the door 
and is connected by a small rubber 







E 






B 

n«M 




1? 






I Ulljc » 











Pneumatic Door Opener 



POPULAR MECHANICS 



tube, F, to a secret mouthpiece placed 
at some convenient location. A small 
piece of spring brass, screwed to the 
door frame, will open the door about 
.hen the operator blows in the 
mouthpiece, or if the door is within 
reach of the mouthpiece, the operator 
can push the door at the same time 
that he blows, thus doing away with 



the spring, which is only used to 
keep the door from relocking. 

One way of making the air connec- 
tion with the outside is to bend the 
tube, F, around and stick it through 
the keyhole. Few burglars would 
ever think to blow in the keyhole. — 
Contributed bv Orton E. White. : _ _: 
Main St, Buffalo, X. Y. 



J* J» J* 

HOW TO MAKE A PADDLE BOAT 



A rowboat has several disadvan- 
The operation of the oars is 
both tiresome and uninter- 
esting and the :?.- ; is 
obliged to travel backwards. 
By replacing the oars with 
paddles, as shown in the il- 
lustration, the operator can 
see where he is going and 
enjoy the exercise much 
better than with oars. He 
can easily steer the boat with 
his feet, by means of a piv- 
oted stick in the bottom of 
the boat, connected by cords 
to the rudder. 

- 1 .: the blacksmith shop 
have a ? *-in. shaft mace as 
shown at A. Fig. 2. It will be neces- 
sary to furnish a sketch giving all the 
dimensions of the shaft, which should 
be designed to suit the dimensions of 
the boat, taking care that sufficient 
clearance is allowed, so that the 
cranks in revolving will not strike the 
operator's knees. If desired, 
split-wood handles may be 
placed on the cranks, to pre- 
vent them from rubbing the 

The bearings. B, can be 
made of hard wood, but 
preferably of iron pipe filled 
with melted babbitt. If bab- 
bitt is used, either thor- 
oughly smoke or chalk the 
shaft or wrap paper around it to pre- 
vent the babbitt sticking. The pieces 
of pipe may be then fastened to the 
boat by means of small pipe straps. 



is may be obtained at any plum- 
ber's at i very small cost. 




Paddle Boat in Operation 

The hubs, C, should be made of 
wood, drilled to fit the shaft and mor- 
tised out to hold the paddles. D. The 
covers. E, may be constructed of thin 
wood or galvanized iron and should 
be braced by triangular boarir as 




Details of Paddle Boat 



is used it should be exposed to the 
weather two or three months before 
painting or the paint will come off. 
spoiling its appearance. 



POPULAR MECHANICS 



Mow to Make ■ Hydrometer 



A home-made hygrometer, for de- 
termining tl • moisture in 
the atmosphere, is shown in the ac- 
companying sketch and 
board, A, with a nail at each end to 



is verj interesting and costs nothing 
to make. — Contributed by Reader, 
I >enver. 




hold the silk thread, B. A 

of silk thread, C, is tied to the 
center of B and connects with an in- 
dicating hand <>r pointer supported by 
the bracket, D. The axle on which 
the pointer revolves consists of a 

■ 'I wood, about tl 
of a lead pencil, with a pin driven in 
each end. A piece of tin, E, is cut V- 
shaped at each end and bent up at 
!■ >r the pins. 
The silk thn 

n axle and is wrapped one or 
two tnms around it. so that when 
the thread is pulled the pointer will 
move on the soak-. It will be noticed 
that the- thread, B, is not perfecth 
straight but bends toward D. 
this reason a very small shrinkage of 
h as occurs when the atmos- 
phere is dry, will cause an increased 

which will be fur- 
ther increased in the movement of the 

pointer. An instrument of this kind 



How to Make a Thermo Battery 



A thermo battery, for producing 

electricity direct from heat, can he 
made of a wooden frame. A, with a 
number of nails. B, driven in the 

piece and connected in 
with heavy copper wires, C. The 

connections should all be soldered to 

• suits, as the voll 

very low and the resistance of an un- 

d joint would ^t<>]> the current. 
The heat may he supplied by an al- 
cohol lamp or other device and the 
current may then he detected by 
imple galvanometer con- 
sisting i.f a square spool of No. 14 
■ >r i') single-covered wire, E, with 1 
Packet compass, F, placed on top. 
Turn the spool in a north and south 
directi-.n or parallel with the compass 
needle. Then when the nail heads 




Thermo Battery 

are heated and the circuit completed 
the needle will swing around it at 
right angles to the coils of wire. Ap- 
plying ice or cold water to the nail 
heads will reverse the current. — Con- 
tributed by A. C. A., Chicago. 



POPULAR MECHANICS 



FOUNDRY WORK AT HOME 



Part Il-How to Make a Mold 



Having finished making the flask and other equip- 
ment, as described in a previous chapter, everything 
will be ready for the operation of molding. It would 
be well for those who have never had any experience 
in this line, to visit a small brass foundry, where 
they can watch the molders at work, as it is much 
easier to learn by observation : but they must not 
expect to make a good mold at the first trial. The 
first attempt usually results in the sand dropping 
out of the cope when it is being lifted from the 
drag, either because of insufficient ramming around 
the edges or because the sand is too drv. 

_ . when the sand is moist enough 

is to squeeze it in the hand. If it forms into a cake 
and shows all the finger marks it has a sufficient 
amount of moisture, but if it fails to cake and crum- 
bles up it is too dry. An ordinary watering pot will 
be found useful in moistening the sand. "but care 
should be taken not - g ±, or the hot- 

metal coming in contact with it when the mold is 
poured will cause such rapid evaporation that the 
mold will -boil" and make a poor casting. A little 
practice in this operation will soon enable the molder 
to determine the correct amount of moisture. 

When molding with sand for the first time it will 
be necessary to screen it all before using it. in order 
to remove the lumps, and if water is added the sand 
should be thoroughly shoveled until the moisture is 
evenly distributed. * The sand is then readv for 
molding. 

The operation of making a mold is as follows : 
The lower half of the flask, or ''-'drag.'" and the 
pattern to be molded are both placed on the cover 
board as shown at A. A quantity of sand sufficient 
to completely cover the pattern is then sifted into the 
drag, which is then filled level with the top with un- 
sand. This is rammed down slightlv with 
the rammer and then more sand is added until it 
becomes heaped up as shown at B. It is then 
ra mm ed again as before. 

It is impossible to describe just how hard a mold 
should be rammed,, but by observing the results the 
beginner can tell when a mold is too hard or too 
soft and thus judge for himself. If the sand falls 
out of the flask when lifting the cope, or if it opens 






n 






H 


- 


• 








: -:-• IN 


G 


r or 
1 








Making a Mold 



42 



POPULAR MECHANICS 



up <>r spreads after il is poured, it 
shows thai the mold has been rammed 
inn little, and if the surface of the 
sand next to the pattern lb cracked it 

• hal the mold has been rammed 
■ I. It will be found thai the 

mold can Btand a little 
more ramming than th«' middle. In 
finishing the ramming, pound evenly 
all ovt with the blunt end 

of the rammer. 

y t-edged rtick, 
, . 

for a 
I ' • 

own it D, and by 

• _■ w ith both hands, as Bhown, 
turn the drag other Bide up. R 

the u] '<"! ana place the 

ope," in 

In order to prevent t 1 • 

the surface 
should be o 
...1 dust. This i- done by shak- 

■ 
i hicli the dust on the pattern 
The 
filled with sand and 
! in . \-.u tlv the same mat 
the -i: 

done a Tin in- 

own at 

mold to the 

pattern, in order to allow th< 

of air and steam when the mold is be- 

\ciii holes • 

i u i ii about the size 

I lie <\<<\\ n through the 

sand until it touches the pattern. The 
"sprue," or pouring-hole, is next cut, 
l>\ mean- of the sprue cutter Bhown at 

i. which consists of a pit 
thin brass or steel tubing about g in. in 
ilian i ■ 

\nw comes the critical part <>f the 

molding that of Lifting the 

!' is h( re that 

the amati ur often becomes discouraged 

sand is liable to fall out of the 

tnd Bpoil the mold, but with a 

little practice and patience the molder 



can lift the cope every time without 
breaking it, as Brio* n at C 

The ne\! operation is that of cutting 
the gate, which carries the molten metal 
from the sprue t«> the opening left by 
the pattern. This is done with a 
a channel being cut about | in. 
wide and aboul I in. deep. The pat- 
tern i- then drawn from the mold, as 
shown at II. by driving a sharp-pointed 
Bteel rod into the pattern and lifting it 
from the -and. When a metal pattern 
is used a thread rod is used, which is 
screwed into a tapped hole in the pat- 
tern. Before drawing it is well to tap 
the drawing-rod lightly with another 
larger rod, Btriking it in all directions 
and thus loosening the -and slightly 
from the pattern. Some n old< 
the pattern gently when withdrawing, 
as -how n at II. in order to loosen any 
sand which has a tendency to stick. 

After drawing the pattern, place the 
cop. back on the drag, as shown at J. 
Place a brick or other flat, heavy objed 
on top of the mold above the pattern. 
to prevent the pressure of the melted 
metal separating th< two halves of the 
mold, ami then pour. The operations 
of melting and pouring will 
scribed in the next chapter. 

Battery Switch 



In cases \\ here batteries are used in 
iries and it is desirable to change the 
strength and direc- 
tion "( the current 
frequently, the follow- 
ing device will be 
found ino-t conveni- 
HQjl cut. In my own case 

I used four batteries, 
but any reasonable 
number can be used. 
Referring to the fig- 
ure, it will be seen 
that by moving the 
-witch. A. toward the 
left the current can be reduced from 
four batteries to none, and then by 
moving the -witch. B, toward the right 
the current can be turned on in the 
opposite direction to the desired 




POPULAR MECHANICS 



43 



strength. In the various positions of 
these two switches the currerr 
each individual cell, or from any ad- 
jacent pair of cells, may be 
either direction. — Contributed bv Har- 

351 Lynda] 
Xorth, Minneapolis. Minn. 



More Uses for Pipe Fittings 



It seems that the number of useful 
articles that can be made from pipes 




Lamp Shade and Dumb Bell Made from 
Pipe Fittings 

and fittings is unlimited. The sketch 
shows two more that may be added to 
the list. A and B are front and side 
views of a lamp screen and C is 

dumbbell. The lamp shade is particu- 
larly useful for shading the eyes when 
reading or writing and. if enameled 
white on the concave side, makes an 
excellent reflector for drawing at 
night, or for microscopic work. 

The standard and base., which con- 



• - - an ordinary pipe flange bushed 
down to receive the upright nipple, are 
enameled a and if the de- 

n a polished table, 
to the 
to hoi the fan 
in the nipple consists in using a small 
a 
The dumbbells are made of short 
pieces of f-in. pipe with H-in. coup- 
lings fastened to each end by pouring 
melted lead in the space between the 
pipes and the couplings. The appear- 
ance is greatly improved by enameling 
black, and if desired the handles may 
red with leather. — Contributed 
::. Warren. M. D.. Xorth Easton. 

Optical Illusions 



By giving the page a revolving or 
rinsing motion the figures appear to 
rotate. The best effect will be pro- 
y laying the book down flat on 
- : - " - and revolving, first 
in one direction and then in the oppo- 
site direction, in such a way that any 
given point on the pa,2'e will describe a 
circle of about \ in. diameter. Fig. 1 
then appears to rotate in the same 
direction as the revolution : Fig. 2 ap- 
pears to revolve in the opposite direc- 
tion, and Fig. 3 appears to revolve 
sometun » - 3 ..-. : fci m and at 

other times in the opposite direction. 

A curious effect can be produced with 
Pig. 1 by covering up Figs. 2 and 3 
with a piece of plain paper and laying 




Move Rapidly with a Rinsing Motion 



POPULAR MECHANICS 




;i coin or other small object od the 
paper. If the vision is then concen- 
trated on the coin or other objeci while 
.shim' is being revolved, Fig. 1 will be 

seen to rotate. 

» • ♦ 

A Home-Made Telephone Receiver 

A telephoi ■ I ba1 will do 

g I work and which may be buill very 

cheaply, can be made as Follows : For 
the caae use an or- 
dinary J-lb. baking 
powder box with a 
I heavy wire 
soldered on the in- 
side, i & in. from 
torn. For the 
magnei use a piece 
of round hardened 
steel mIh.hI 3 in. in 
diameter and l { in. 
iiL r . If desired, a 
n (i I d 
round file may be 
used for the magnet 
core, which should be magnetized pre- 
tnbling, either by passing 
a current of electricity around it, or 
by direct contad with another magnet. 
The Bteel core should be wound with 
aboul v 36 insulated wire, 

which should l" soldered 
to ;i piece of lamp cord, passed through 
:i hoh- in the bottom of the can and 
knotted .inside to prevent pulling out. 
A disc of thin Bneet-iron, such as is 
used by photographers for tintypes 
pe i. should be <ut to the di- 
ameter of the can, taking care not to 
bend the iron. The magnet Bhould 
then be placed in the bottom of the 
can in an upright position and enough 
of a melted mixture of beeswax and 
resin poured in to hol3 it in position. 
While the wax is -till in a plastic 
condition the magnet should be Located 
centrally and adjusted bo thai the end 
will be h in. or less below the level of 
the top of the copper ring. 

After the wax has hardened the disc 
is -lipped iii and fastened tightly by a 
ring of solder when the instrument is 
ready for use 



How to Make a Rain Gauge 




An accurate rain gauge may be 
easily constructed from galvanized 
iron, as shown in the sketch herewith. 
The funnel, A, 

01 e r 1 a p s and 
rests on the 
body, B, and dis- 
charges into the 
tube, C, the area 
of which is 1/10 
thai of the top 

of the funnel. 

The depth of the 

water in (' is 

thus ten times 

the actual rain- 
fall, so that by 
measuring i t 

with a - t i c k 
marked off in 
tenth- of an 
inch, we obtain 
the resull in 

hundredths of 
an inch. 

A good size to make the rain gauge 
is as follows: A. 8 in. diameter; C, 

2 53 1"" in.: length of C, about 20 in. 
It Bhould he placed in an exposed loca- 

that no inaccuracy will occur 
from wind currents. To find the fall 
of -now. pour a known quantity of 
warm water on the snow contained in 
the funnel and deduct the quantity 
poured in from the total amount in 
the tube.— Contributed by Thurston 
llendrickson, Long Branch, X. J. 

» • ♦ 

An experienced photographer uses 
blacklead for grooves about a camera 
or holder. A small quantity is rubbed 
well into the grooves and on the edges 
of shutters that refuse to slide easily 
with gratifying results. Care must be 
taken to allow no dust to settle in the 
holders, however. 

» • ♦ 

The Colorado river broke its banks 
again December 9 and the Salton sea 
is rising once more, reminding one of 
Mulligan's "off again; on again; off 
again." 



POPULAR MECHANICS 



S* Amateur Mechanics i *& 



Young Mechanic Builds Successful 
Auto 



The building of a small runabout 
is not such a difficult problem as would 
be imagined by those who have never 
tried it. All the machine work on 
mine was done on a small foot-power 
rheels, 
ceis, hubs and 
parts were taken from 
bicycle and motorcycle 
fittings. 

The "engine is of the 
4-cycle type and was 
modeled after an ordinary 
motorcycle engine. The 
crank ease 

and made in two pieces 
with a longitudinal joint 
and a bearing in each 
half. Enclosed in the 
crank case are two fly- 
wheels, connected by a 
small pin. which :- 
: : i f ae crank pin. A 
small pulley on the en- 
gine shaft is connected 

to a larger pulley on a 

countershaft, directly un- 
der the operator's feet, 
by means of a slack belt, 
which may be tightened by means of a 
swinging idler pulley, operated by a 
hand lever. When the belt is slack 
the engine will run at full speed with- 
out driving the machine, but a very 
little pull on the lever will tighten the 
belt and perform the function of a 
clutch. 

The drive from the countershaft to 
the rear axle is by means of a bicycle 
chain and sprocket. I used no differ- 
ential gear on my machine, as I found 
that the hubs, which are of the "'coast- 
er' pattern, successfully prevent any 
slipping when turning a corner. 

The frame of the car is built of 



white ash with 1 in. by 2 in. sills, and 
the axles are made of lf-in. heavy steel 
tubing. The seat is made ol white 
wood with band-iron corners inside, to 
stiffen it. and is upholstered in imita- 
tion leather. — Contributed bv Fred W. 
Pickles. 692 Wealthy Ave., Grand 
Eapids, Mich. 




Auto Built by 15-Year-Old Boy 

A Handy Ice Chisel 



Fishing through the ice is great 
sport, but cutting the first hoi 
paxatory to setting the lines is not 
always an easy task. The ice chisel 
described below will be found very 
handy, and can be made at very slight 
expense. 

In the top of an old axe head drill 




C-:c:>i:i;3 Axe a-i \;-i Chisel 






POPULAR MECHANICS 



hole, and then tap it tor 
gas pipe, about 18 in. long. I 

. r i ad of the pipe, and wre* on 

iin ..M mow shovel handle. When 

. h the two pieces 

i and vnu have your chisel 

handle may be included 

in tin outfit When the boles are fin- 

,im<I your lin< w the 

■ mi the head of the axe, put in 

the handle and your a* is read) to cut 

i keep your 
Contributed by C. J. Band, west 

♦ • ♦ 

Home-Made Arc Li^ht 



a inding an electric bell 

with Mo. 16 \\ ire and connecting it in 

arbons, 

own ni the 

sketch, ;i -mall arc 

will be formed !»•- 

the carbon 

applied. In 

•• li. A is the 

bell magnet ; 

B, the armature ^ 

-li- : ;illd E 

B, binding - 

mnected 

wnli l" ..I- 18 dry 

*■- •— • 

Electric Door Opener 




nvenienl and efficient de- 
li any door fitted with 
mown in tli«' accom- 
panying sketches. A I'airU stiff spring, 
•■ .1 b) a flexible wire cord 
i,, tli, knob B. 'I'lir cord i- also fas- 
tened to a lever, ( '. which is pivoted at 
It and a magnetic trig- 

. ii ade from the armature an, I 
magnet of an old elect tic bell. 
When the circuit is completed by 
i ontact device out- 



2D 



Ob 



Apparatus Placed on In.slde of Door 

Bide the door, tin' magnet, F, pulls 
do* n the armature which releases the 

and allows the Bpring to open 
the luck. I f there are metal numbers 
on tl iii-ul, of the door they may be 

i tin- -• cret < ontact, it' desired, 
hut if there are oo numbers on the 
small contact board may be 
constructed by <lri\iiiL r about 12 brass- 
headed tacks mi" a thin piece of wood 
ami making connections at the hack as 
shown in the wiring diagram. 

In this particular diagram the tacks 
numbered l an, I : are used I'm- unlock- 

door, the others being connected 
with the electric bell circuit as indi- 
cated for the purpose of giving an 
alarm should anybody try to experi- 
ment with the secret contacts. By 
means of a pocket km fe or other metal 
article the operator can let, himself in 
at any time by connecting the tacks 
numbered 1 and ", . while a person not 
knowing the combination would he 
liable to sound the alarm, of course 
the builder of this device can choose a 
combination of his own and can thus 

■ .m\ body else from entering the 




Wiring Diagram 



POPULAR MECHANICS 



47 



door; even those who read this descrip- 
tion. — Contributed by Pern- A. Borden, 
ison University. Gachvilie, X. B. 



Foundry Work at Home 



Part 111— Melting and Pouring 



Having prepared one or more molds 
• ribed in the last chapter, the 
nest operation is that of melting and 
pouring. An ordinary east-iron glue 
pot makes a good crucible and can be 
easily handled by a pair of tongs, made 
out of- -hown in the sketch. 

In order to hold the tongs together a 
small link can be slipped on •: 




Pouring the Moid 

handle, thus holding the crucible se- 
curely. 

A second piece of steel rod bent in 
the form of a hook at r. 
useful for supporting the weigh: : the 
crucible and prevents spilling the mol- 
ten metal should the tongs slip off the 
crucible. The ho :ul for 

removing the crucible from the fire, 
which should be done soon after the 
metal is entirely melted in order to 
prevent overheating. The metal should 
be poured into the mold in a small 
stream : _ the air a chance to 
escape and should not be poured di- 
rectly into the center of the opening, 
as the metal will then strike the bottom 
hard enough to loosen the sand, thus 
making a dirty ca- 



lf after being poured the mold sput- 
ters and emits large volumes of 
sand is too « 
the castings in such eases will probably 
be imperfect and full of holes. 

A mold made in the manner pre- 
viously described may be poured with 
any desired metal, but a metal " 

uelted will g: rouble. 

One of the easiest metals to melt and 
one which makes 

gs is pure tin. T Is at a tem- 

p-ratu d bove the melting 

point of solder and although somewhat 
expensive the permanent br:_ 
and silverlike appearance of t. 

. is very desirable. A good 
metal" may be made bv mixin_ 

line, and 5 
mony. The object of adding antimony 
to an alloy is to prevent shi 
when cooling. 

A very economical alloy is made by 
melting up all the old type metal, 
babbitt, battery zincs, white metal and 
other scrap available, and ad 

r-tiniony if the me: 
much in cooling. If a good furnace is 
available, aluminum can be melted 
without any difficulty, although this 
metal melts at a higher temperature 
than any of the metals pr 
:: :ir :. 

In : _ a sepa- 

rate crucible, used only for zinc, is very 
desirable, as the presence of a very 
small amount of lead or other impurity 
;se the batteries to polar: 
_ jd way to make the binding- 
posts is to remove the binding-posts 
from worn-out dry batteries and place 
them in the molds in such aw 
the melted zinc will flow around them. 

The time required for a casting to 
solidify varies with the size and shape 
of the casting, but unless the pattern 
is a very large one about five minutes 
will be ample time for it to set. The 
. - v : . ::: \ '/: 

and the sand brushed off. The gate can 
be removed with either a cold chisel or 
a hacksaw and the easting is then ready 
for finishing. 



POPULAR MECHANICS 



Steam Engine Built in Amateur 
Shop 



Lighting Incandescent Lamp with 
Induction Coil 




"Power Is About 1 1-2 Hp." 

coupling at the center and mounting 
on separate beds. 

The complicated steam chests used 
in many engines are replaced in this 
one by simple cylinder valves with 
Bimple stuffing boxes, which may be 
taken from globe or angle valves, if 
the builder does not wish to construct 
them himself. The cylinders of this 
engine are 2± in. diameter and the 
stroke is 3 in. With a steam pressure 
of 80 lb. acting on both cylinders 
and a speed of 250 r. p. m. the power 
is about 1^ hp. — Contributed by Dr. 
Mark G. McElhinney, Ottawa, Canada. 



The amateur mechanic who has a 
Lit lie and Bhaper in his equipment may 
possibly be encouraged to build an en- 
gine along similar lines to the one 
here illustrated. In this engine, as in 
almost every engine, the cylinder and 
bed are of cast iron, hut the frame is 
constructed of cold-rolled steel. The- 
two units shown are exacl duplicates, 
either of which may be run independ- 
ently of the other by disconnecting the 



An incandescent lamp of low candle- 
power may be illuminated by connect- 
ing to an induction coil in the manner 
shown in the sketch. One wire is con- 




Qeissler Tube 



nected to the metal cap of the lamp 
and the other wire is fastened to the 
glass tip. If the apparatus is then 
placed in the dark and the current 
turned on. a peculiar phosphorescent 
glow will fill the whole interior of the 
lamp. The induction coil used for this 
purpose should give a spark about ^ in. 
Ion- or more. — Contributed by Joseph 
B. Bell, 411 Herkimer St., Brooklyn, 
New York. 



Relay Made from Electric Bell 



It is not necessary to remove the ad- 
justing screw when changing an elec- 
tric bell into a re- 
lay. Simply twist it 
around as at A and 
bend the circuit- 
breaking contact 
back as shown. It 
may be necessary to 
remove the head of 
the screw, A, to pre- 
vent short-circuiting 
with the armature. — Contributed by 
A. L. Macey, 231 West 40th St., New 
York City. 






POPULAR MECHANICS 



HOW TO MAKE A BOX KITE 



As some of the readers of this maga- 
zine mar desire to build a box kite. 
a simple method of constructing one 
of the modern type is given in detail as 
follows : The sticks should be made of 
straight-grained wood, which may be 
either spruce, basswood, 
or white pine. The lon- 
gitudinal corner - - 
A A. should be f in. 
square by 12 in. long, 
and the four diagonal 
struts. B. should be + in. 
by ^ in. and about 26 
in. long. 

Two cloth bands 
should be made to the 
exact dimensions given 
in the sketch and fast- 
ened to the four longi- 
tudinal sticks with 1 oz. 
tacks. It is well to mark 
the positions of the 
sticks on the cloth bands, 
either with a soft lead 
pencil or crayon, in order 
to have the four sides of 
each band exactly equal. 
The ends of the bands 
should be lapped over at 
Least | in. and sewed 
double to give extra 
strength, and the edges should be care- 
fully hemmed, making the width, when 
finished, exactly 12 in. Probably the 
best cloth for this purpose is nainsook, 
although lonsdale cambric or light- 
weight percaline will answer -nearlv as 
well. 

The diagonal struts, B, should be 
cut a little too long, so that they will 
be slightly bowed when put in posi- 
tion, thus holding the cloth out taut 
and fl? They should be tied to- 
gether at the points of intersection 
and the ends should be wound with 
coarse harness makers thread, as 



shown at C, to prevent splitting. The 
small guards, D, are nailed or glued 
to the longitudinal sticks to prevent 
the struts slipping out of position. Of 
course the ends of the struts could be 
fastened to the longitudinal strips if 
desired, but if made as described the 
kite may be readily taken apart and 




rolled up for convenience in carrying. 
The bridle knots, E, are shown in 
detail at H and J. H is a square 
knot, which may be easily loosened 
and shifted to a different position on 
the bridle, thus adjusting the lengths 
of F and G. A bowline knot should 
be tied at J, as shown, to prevent 
slipping. If the kite is used in a light 
wind, loosen the square knot and shift 
nearer to G. thus shortening G and 
lengthening F, and if a strong wind 
is blowing, shift towards F. thereby 
lengthening G and making F shorter. 
In a very strong wind do not use the 



POPULAR MECHANICS 



bridle, but fasten a string securely to 
the Btick at K. — Contributed by Edw. 
B. Harbert, kite expert, L627 Briar 
Place, Chicago. 



Pictures Without a Camera 



[f yon wish to take a picture and 
have oo camera, bul would like to gain 
a little experience in finishing up, yon 
can make some \'i\ oice pictures by 
the following method. Or, if you 
have a proof and have broken your 
plate after you took that proof, you 
can make another <>n«\ aboul as 
is the original, without tak- 
ing the picture over. Of course, it is 
oot possible to take an out-door scene 
without a camera of some sort, as ex- 
posing the plate to the light ruins it, 
and ii' found, bul you can 

take pictures of other pictures with- 
out a < amera. 

All you need is a dry plate, a print- 
ing Frame, the size ot larger than the 

picture von w ish to take, and the usual 

developing outfit. < !ut a picture, \\ ith 
nothing on the other Bide, out of a 
ne. or take an) ordinary camera 
picture, not mounted — this we will 
take our picture of. 

In your printing frame place a piece 
of very clean glass the Bize of the 
frame; an old plate from which the 
gelatine has been removed bj hot water 




Made Without Camera 

i- beat Place your picture in the 
frame on top of the glass, face up. 
i Better results « ill be had if the pic- 
ture is oiled with kerosene on the back 
side, but don't let oil get on plate.) 
Then lay your plate u ith the sensitive 
side next to the face of your picture, 
put in the frame hack, as yon would 
in printing a picture, and fasten it 
tight. Of course, this is done in the 
dark room. Now you are all ready for 
the exposure. After a little practice 
you will have no trouble in judging 
the time. It depends upon the picture, 
the light and the plate. The best way 



Experiment With Colored Electric Lamps 



To many the following experiment may be much 
nmre easily performed than explained: Place the 

hand or other object in the light coming from 
two incandescenl lamp-, one red and one white, 
placed about a foot apart ami allow the shadow 
to fall on a white Bcreen such as a table cloth. 
Portions of the shadow will then appear to be a 
bright green. A Bimilar experiment consists in 
first turning on the red light for about a minute 
and then turning it off at the same time that 
the white one is turned on. The entire 
will then appear to be a vivid green for about 
second, alter which it assumes its normal 
color. 




POPULAR MECHANICS 



-jen the little window of your 
dark room and expose the frame about 
a second in the subdued daylight. Be- 
move the plate carefully and develop 
in the usual way. There will be a 
negative of the picture you had at first; 
if you have been successful, if not. you 
should try it a time or two, varying 
the time of exposure. 

In this manner you can make many 
prettv blue prints for your wall, or 
supply yourself with postal pictures of 
things impossible for you to take a 
picture of yourself. 

Should you have trouble with your 
high lights, print rather dark and 
bleach in following solution: 

Water. 100 ec 

Potassium Ferrievanide (1A0 soL), 3 ec. 

Hrpo <1 10 soL), 20 cc. 



Wireless Telegraph 



The accompanving diagrams show a 
wireless telegraph system that I have 
used successfully for signaling a dis- 
tance of 3,000 ft. The transmitter 
consists of an induction coil, about the 
size used for automobiles, a key or push 
button for completing the circuit and 
five dry batteries. The small single 
point switch is left open as shown 
when sending a message, but when 
receiving it should be closed in order 
that the electric waves from the an- 
tenna may pass through the coherer. 
The coherer in this case is simply two 
electric light carbons sharpened to a 
wedge at one end with a needle con- 
necting the two, as shown. An ordi- 




nary telephone receiver is connected in 
series with the coherer, as show-. T 
receive messages hold the receiver to 
the ear and close the switch and an- 
swer by opening the switch and operat- 
ing the kev. — Contributed bv Coulson 
Glide, 816 X. Temple Ave., Indian- 
apolis, Ind. 



Constant Pressure Hydrogen Gen- 
erator 



By fitting three bottles.. A. B. C . with 
rubber stoppers and connecting with 
glass tubes as shown in 
the sketch, hydrogen or 
other gases produced in a 
similar manner may be 
generated under constant 
pressure. In making! 
hydrogen, bottle B is part- 
ly filled with zinc nodules 
formed by slowly pouring 
melted zinc into water. 
Hydrochloric acid is then 
poured in the small fun- 
nel, thus partly filling 
bottles A and C. When 
the acid rising from C 
comes in contact with the 
zinc, hydrogen gas is gen- 
erated and fills bottle B. 
The gas continues to gen- 
erate until the pressure is 





Wiring Diagram for Wireless Telegraph 



bottle C, when the acti 

ceases. As fast - the gas is nsed the 

acid rises in the tube and generates 

constant, the pressure depending on 
-~:_z ;±::t::t \tT _i ::ie '.- "-- :z :lie 
acid in bottle A and bottle B. A 
device is easily upset, a ring stand 
should be used to prevent its being 
broken, or if it is to be a permanent 
apparatus it- may be mounted on a 
substantial wooden base. This ap- 
paratus may also be used for preparing 
acetylene gas or almost any gas which 
requires a mixture of a solid and liquid 
in its preparation. — Contributed by C. 
S. J., Detroit, Mich. 



POPULAR 
MODEL LOCOMOTIVE 



MECHANICS 



The illustration Bhowa a model loco- 
motive buill bj R03 C. Beaver, a stu- 
dent in the Greenville (Pa.) Bigh 



ture will work bettor, as this will pre- 
sent the magnetism from acting on 
both ends of the armature. 

The wiring diagram. Fig. 2, shows 
how tlic connections are to be made. If 




M<dcl Locomotive Made by Roy C. Beaver 

DIMEN8IONB Cylinder, '-"•_• In. liy l '■_. In. . ralve travel, % in. 

diameter of boiler, emalli i die ter driving wne 

.si. and tender I 



flre boa, 4 In. by 6 In.; 
height to top of stack, 



Bchool. This model, which is built 

almost entirely of \\ I. required 20 

months' time for its construction and 
was made from pencil sketches, drawn 
from a Bessemer and Lake Erie loco- 
motive. 

All the part- were worked oul in 
detail, including the link motions and 

other in«»ving part-, and when moved 

along the track it run- very Bmoothly. 
HOME-MADE ANNUNCIATOR 



the push button A is closed the bell 
will ring and the pointer will point at 



When one electric bell is operated 
from two push buttons it is impossible 
to tell which of the two push buttons 
is being operated unless an annuncia- 
tor OT similar device is nsed. A very 
simple annunciator for indicating two 

numbers can be made from a small box. 

Fig. 1. with an electric bell magnet, 
A. fastened in the bottom. The arma- 
ture, p,. is pivoted in the center by 

means of a small piece of wire and has 
an indicator or hand. C. which moves 

to either righl or left, depending on 
which half of the magnet is magnet- 
ized. If the back armature, D, of the 
magnet is removed the moving arma- 




Annunciator and Wiring Diagram 



1. while the closing of the push button 
B will ring the bell and move the 
pointer to 2. — Contributed by H. S. 
Bott, 109 Cooper St., Beverly, N. J. 



Experiments are being made with 
brown sugar which is said to greatly 
increase the adhesive properties of 
mortar. Equal parts of sand and lime 
are mixed. 



POPULAR MECHANICS 



Amateur Mechanics I «£jfc 



How to Make an Ammeter 



Every amateur mechanic who per- 
forms electrical experiments will find 
nse for an ammeter and for the bene- 
fit of those who wish to constrv. 
an instrument the following descrip- 
tion is given : The operative principle 
of this instrument is the same 
of a galvanometer, except : 
working position is not con fin ed to the 
magnetic meridian. This is accom- 
plished* by making the needle revolve 
in a vertical instead of a horizontal 
plane. The only adjustment neces- 



long, or long enough to reach between 
the two screws shown in Fig. 2. The 
ends of this small axle should be ground 
pointed and should turn easily in the 
cavities, as the sensitiveness of the in- 
strument depends on the ease with 
which this axle turns. 

After assembling the core as shown 
in Fig. 4, it should be filed a little at 
one end until it assumes the position 
indicated. The pointer or bar. 

- made of wire, aluminum being 
preferable for this purpose, although 
copper or steel will do. Make the wire 
4| in. long and make a loop, D, i in. 




Fig. 2 



Complete Ammeter and Details 



sary is that of leveling, which is ac- 
complished by turning the thumb 
screw shown Wig. 1, until the 

hand points to on the scale. 

First make a support. Fig. 2 . 
bending a piece of sheet brass to the 
shape indicated and tapping for the 
screws, C C. These should have hol- 
low ends, as shown, for the purpose of 
receiving the pivoted axle which sup- 
ports the hand. The core. Fig. :. is 
made of iron. It is 1 in. long, ^ in. 
wide and J in. thick. At a point a 
little above the center, drill a hole as 
shown at H and through this hole drive 
a piece of knitting needle about \ in. 



from the lower end. Solder to the 
short end a piece of brass, E, of such 
weight that it will exactly balance the 
weight of the hand. This is slipped on 
the pivot and the whole thing is again 
placed in position in the support. If 
the pointer is correctly balanced it 
should take the p :-::::: shown in Fig. 
1, but if it is not exactly right e little 
filing will bring it near enough so that 
it may be corrected by the adjusting 
screw. 

Next make a brass frame as shown 
in Fig. 6. This might be made of 
wood, although bras; is better, as the 
eddy currents set up in a conductor 



POPULAR MECHANICS 



surrounding a magnet tend to Btop 
oscillation of the magnet. (The core 

gnetized when a current flows 
through the instrument) The brass 
frame is wound with magnel wire, the 
size depending on the Dumber of am- 

to be measured, Mine" is wound 
with two layers of X<>. 1 1 wire, LO 

■ ,, each layer, and ia aboul right 
for ordinary experimental purposes. 

ads ,,f the wire are fastened to 
the binding-posts, B. C, Fig. L. 

A « I. n box, l>. i- th« d made and 

provided with a glass front A piece 
of paper ia pasted on a piece of wood, 
which ia then fastened in the box in 
TO ch a position thai the hand or point- 
to the paper acale. 
The box ia •"•', in. hieh, 1 in. wide and 
jeep; inside measurements. 
Ui.t everything ia assembled put a 
drop of wider on the loop at 1' 



| (l prevent il turning on the axle. 
To calibrate the instrument connect 
ae shown in Fig. 7, where A is the 
home-made ammeter; B, a standard 
ammeter; C, a variable resistance and 
1 ) a battery, consisting of three or more 
cells connected in multiple. Throw in 
enough resistance to make the stand- 
ard instrument read 1 ohm and then 
put a mark on the paper scale of the 
instrument to be calibrated. Continue 
in this way with 2 amperes, 3 amperes, 
•1 amperes, i tc., until the scale is full. 
To make a volt ter out of this in- 
strument, wind with plenty of- No. 36 
magnet wire instead of No. 1 I. or if it 
is desired to make an instrument for 
measuring both volta and ampere-, use 
both windings and connect to two pairs 
of binding-posts. — Contributed by J. 
E. Dussault, 828 Chs. Borromee St, 
Montreal, Can. 



Cheap Telegraph for Learners 

An inexpensive telegraph instrument 
can be made by fastening an 
hell magnet, A. to a small wooden box, 
inch aa a cigai box. 

| eet-iron arma- 

ture is p rovi d ed 
With B tapper. B, 

which consists of a 
small bolt and nut 
The anvil, C, and 
stop, 1>. are also 
made from bolts 
and are fastened to 
I 
B, bent as 
shown. The key, F, 
is made of brass 
aboul l 32 in. thick 



Burning Inscriptions on Trees 



Jk/ytAif/o^ Scrvi* 




Scrape off the bark just enough to 
come to the first light under coating, 
which is somewhat moist. With a 
lead pencil make an outline of the in- 
scription to be burnt on the tree and 
bring the rays of a large magnifying 
glass not quite to a fine focua on the 

The tree will be burnt along the 



^ = \ JoK] Line 



and bo adjusted that it nearly touches 
atact [f a double contact key is 
warned, the adjusting Bcrew may be 
used Cor the second com 

While the instrument as described 
will work only on very short distance 
lines, it may be rewound for use on a 
line 2 or 3 miles long by using about 
single cotton-covered 
Contributed by A. Gk Ward, 
Wilkinsburg, Pa. 



Home Made Telegraph Instrument 

pencil mark-, and if the glass is not 
held in one spot too long, the inscrip- 
tion will be burnt in as evenly as if it 
had been written. — Contributed by 
Stewart EL Leland, Lexington, 111. 



To lubricate sheet metal mix 1 qt. 
whale oil, 1 lb. white lead, 1 pt. water 
and 3 oz. finest graphite. Apply with 
a brush before the metal enters the 
dies. 



POPULAR MECHANICS 



Mechanical Tricks with Cards 



One of the simplest tricks to per- 
form, but one not easily detected, can 
be executed by using a tapered deck 
of cards as shown in Fig. 1. A cheap 
deck of cards is evened up square, fast- 
ened in a vise and planed along the 




edge in such a manner that all the 
pack -will be tapered about 1-16 in. 
This taper is exaggerated in the illus- 
tration which shows one card that has 
been turned end for end. 

It is evident that any card r - 
in this way can be easily separated 
from the other cards in the pack, which 
makes it possible to perform the fol- 
lowing trick : The performer spreads 
the cards out. fan-like, and asks an 
observer to withdraw a card, which is 
then replaced in any part of the pack. 
After thoroughly shuffling the cards 
the performer then holds the deck in 
both hands behind his back and pro- 
nouncing a few magic words, produces 
the card selected in one hand and the 
rest of the pack in the other. This is 
accomplished by simply turning the 
deck end for end while the observer 
is looking at his card, thus brii a - 
the wide end of the selected card at 
the narrow end of the pack when it 
is replaced. The hands are placed be- 
hind the back for a double purpose, as 
the feat then seems more marvelous 
and the observers are not allowed to 
see how it is done. 

In prize games, players having the 
same score are frequently called upon 
to cut for low to determine which shall 
be the winner, but a fairer way is to 
cut for high as a person familiar with 
the trick shown in Fig. 2 can cut the 
cards at the ace, deuce, or three spot, 



nearly every time, especially if the 
deck is a new one. This is done by 
simply pressing on the top of the deck 
as shown, before cutting, thus causing 
the increased ink surface of the high 
cards to adhere to the adjacent ones. 
A little practice will soon enable one 
to cut low nearly every time, but the 
cards must be grasped lightly and the 
experiment should be performed with 
a new deck to obtain successful results. 
— C ratributed by D. B. J.. Chicago. 



How to Make a Porch Chair 

The illustration shows a very com- 
fortable and attractive porch chair that 
can be made with few tools and easily 
procured material. Most any kind of 
wood will answer, says the American 
Carpenter and Builder, but if open 
grained wood, such as oak or chestnut. 




Porch Chair Finished 

is used the parts should be filled with 
a paste filler. If the natural color of 
the wood is not desired, the wood may 
first be stained, the filler being colored 
somewhat darker than the stain. 

Procure enough lumber to make all 
the pieces shown in the detail draw- 
ing and finish to the dimensions shown, 
being careful to make the correspond- 
ing pieces exactly alike in order to pre- 
serve the perfect symmetry which is 
- try in work of this kind. In bor- 
ing the holes care must be taken to 



POPULAR MECHANICS 











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tli edges of the holes Bharp and 
clean. The holes Bhonld each be bored 
until the Bpnr shows; the bil should 
then 1"' withdrawn and the rest of the 
boring be done from the other Bide. 

micirculaT notches arc made by 
placing the two pieces edge to edge in 

■ ami placing the spur of the 
bit in • The L-in. bil is ua d. 

Aa ii will be difficull to finish the bor- 
ing of these blocks from the second 
parts remaining may he cut 
nut with the knitV after the pieces have 
been separated. 

Five J-in. dowel rods are needed. 
It is possible to get these in one long 
you happen to live near a mill 
and then all you will have to do is 
to saw off the desired Lengths. How- 
ever, if they cannot he pot easily you 
can make your own. Two rods each 
is' in. Long; two rods each 20^ in. and 
one rod -y!\ in. give the exact lengths. 
It is well to cut each piece a little 
longer than required so that the ends 
which are imperfectly formed may he 
cut off. These rods should fit tight 
and may be fastened in addition with 
a small screw or nail from the under 
or hack 



10 


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at- 


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Details of Home Made Porch Seat 

The hand rests should be nailed to 
the arms with small nails or brads be- 
fore the arms are bolted. The illus- 
tration of the assembled chair shows 
the relative position. 

The bolts should be \ in. and of the 
following lengths : 4 bolts 2\ in. long ; 
2 bolts 2 in. long; 2 bolts 3 in. long. 
Washers should be placed between ad- 
jacent pieces of w r ood fastened together 
with bolts and also at both ends of the 
bolts. This will require 26 washers in 
all. While the size of the chair may 
be varied, it wall be necessary, to keep 
the proportions if the parts are to fold 
properly. 



To make black ruling ink, take good 
black ink and add gall as for blue. 
Do not cork, or it will not turn black. 



POPULAR MECHANICS 



How to Receive Wireless Telegraph 
Messages with a Telephone 



Easily Made Book Shelf 



By A. E. Joerin, Wireless Telegraph Demonstrator 



Any telephone having carbon in the 
transmitter (all ordinary telephones 
have carbon transmitters) can be used 
to receive wireless messages, by simply 
making a few changes in the connec- 
tions and providing a suitable antenna. 
Connect the transmitter and receiver 
in series with three dry cells and run 
one wire from the transmitter to the 
antenna. Connect the other transmit- 
ter wire to a water or gas pipe in order 




Wiring Diagram for Wireless Telegraph 

to ground it, and then hold the re- 
ceiver to your ear. Any wireless tele- 
graph message within a radius of one 
mile will cause the transmitter to act 
as a coherer, thus making the message 
audible in the receiver. 

By using an ordinary telephone 
transmitter and receiver and a -|-in. 
jump spark coil, a complete wireless 
telegraph station can be made, which 
will send or receive messages for a 
radius of one mile. The accompanying 
wiring diagram shows how to make the 
connections. By putting in an extra 
switch three of the sending batteries 
may be switched in when receiving, 
thus obviating the necessity of an extra 
set of batteries. 



A very cheap but useful and attract- 
ive book shelf is shown in the accom- 
panying drawing. The vertical strips, 
A, may be f in. by 2 
in. and are screwed 
to four shelves, B, 
each cut to the 
shape of a quarter 
circle. The screws 
are all countersunk 
and as the heads all 
come on the side 
next to the wall, 
they do not show. 
The design might 
be varied somewhat 
to suit the fancy 
of the builder, i 
though the appear- 
ance of the shelf """"" ■*"""" 
constructed as shown is very pleasing, 
especially so if the workmanship is 
good and the wood carefully stained 
and varnished. The total cost of the 
one I made was less than 75 cents. — 
Contributed by Geo. C. Murphy, 412 
Critenden St., Owensboro. Kv. 




Breaking in a New Pen 



There are many ways of breaking in 
a new pen, such as moistening in^the 
mouth, wiping on a 
blotter, dipping in 
the ink and rubbing 
on the edge of the 
ink well, etc., but 
the best way that I 
have found is to hold 
a lighted match un- 




der the pen for just an instant and 
then plunge immediately into the ink. 
This will effectually remove all the oil 
or grease on the surface and, unless 
the pen is overheated, will not draw 
the temper. — Contributed by A. C. 
Pearson, Duluth, Minn. 



POPULAR MECHANICS 



How to Make a Jump Spark Coil 



By the New Unhand Coll Winding Co. 



The induction coil is probably the 

most popular piece of apparatus in the 

electrical laboratory, and particularly 

i- it popular because of its use in 

experimental wireless telegraphy. Ten 

ago « ireless ti l< graph] was ;i 

dream of scientists; today it i- the 

plaything of school-boys and thousands 

- well. 

ited of oearly all technical 

. «!■ may briefly describe an 

induction coil as a Btep-up transformer 

ill capacity. It comprises a core 

lindricaJ bundle of 

-nft iron trires cui to proper length. 

B mi uu nf two or more layei - 

l i or No. 16 magni I w ire, wound 

evenly aboul tins core, the bundle 

d when the wire 

term ins 

electricity. 

Should we dow -liji over this electro- 
magnel a paper tube upon which has 
been wound with regularity a 
and continuous length of No. 36 mag- 
re, it w ill be found thai the lines 
of force emanating from the energized 
Dew coil winding 
almosi as though it 
hut ii part of the Bur- 
rounding air itself, and 
when the battery cur- 
rent is broken rapidly ;i 
d electrical current 
aid to be induced 
into the Becond coil or 
lary. 
All it any of the 
I'.irt < of an induction 
coil may lie puri 
ready - made, and the 
tir-t thing t-i iln i.- in 
decide which of the 
farts the amateur me- 
chanic c;m make and 
Which Would he tx 

to buy ready-made. If the builder has 
had no experience in coil winding it 
would probably pay to purch 

lary coil ready-wound, as the 
operation of winding a mile or more of 



tiin wire i- very difficult and tedious, 
and the results are often unsatisfac- 
tory. In ordering the secondary it is 
always Decessary to specify the length 
of spark desired. 

m!iiu in- method of completing 
a 1-in. coil illustrates the general de- 
tails of the work. The sann methods 
and circuits apply to smaller and larger 
The ready-made secondary is in 
solid cylindrical form, aboul 6 in. long 
and gjj in. diameter, with a hole 
through the winding l| in. in diameter 

as shown in Fig. 1. The secondary 

will stand considerable handling with- 
out tear of injury, and need not he set 
into a case until primary i- completed. 
The primary i- made of line annealed 
noli w ire cut T in. or 8 in. in 
length, as the maker prefer.-, and 
bundled to a diameter oi I in. The 
may he straightened by rolling 

two oi" three ;|t a tlllie hetWeill t WO 

of hard w 1. If the amateur 

has difficulty in procuring tin- wire, 
the entire (ore may he purchased 
ready-made. 

After the core wire- are bundled, the 
Wrapped with one or two layers 

of manila paper. The straighter the 
wire the more iron will enter into the 
construction of the cure which is de- 




Wiring Diagram and Parts of l-ln. Induction Coil 

sirable. Beginning half an inch from 
one end. No. Hi cotton-covered magnet 

wire is wound from one end to the 
other evenly and then returned, mak- 
ing two layers, and the terminals tied 



POPULAR MECHANICS 



down to the core with, twine. Core and 
prima: 

paraffine waz anal] quan- 

: : ii: 

. wax may be 

.. intf 
a box. Over this primal is now 
wrappe tape, or 

oes8 of ] - 

I 
i 

~e been pur- 
chased d box of 
mahogany or large enong 

I spare all 

- iti 

- -\ k this wtnrkj :.. ' . I 
I 

: ": :rr"J 
in the : 
the primary core This 

i tc ; used 1 I . 

ally the _ inter- 

file wfl aped as 

in Pig. - ; fas I to the box in 

such a way that t 
I I 
- 

side the bos 
affixing- the 
The c : i 
:: thin g I 5 in. 

and a s 
foil. hen cot and 1 
tinuous length, ach piece ad tin-foil 
must overlap the i Ij wning 

" : i d attn is elec- 

trical circuit. In shaping the eon- 
denser, one piece ol Hie paper is laid 
down. then the strij :z tin-foil, then 
sti ij - :: iper ind an jtb a layer 

I ind finally the fon I 
paper. This makes a oondensex which 
may be folded, beginning at one end 
and bending rat in at : time. 
The amdensei :- nes I : securely 

with bands of ] per oris I bofle i 

in pure paraffine wax ft 
after which it is ":7 ; :t: nndex ::o-A- 
erable weight until firm and hard >ne 
:f the sheets : tin-foil : : tc : urn me 
pole of the Mmdensei and the nthei 
sheet, which is insulated from :':: first, 



forms ti .- or terminal. 

• . . .1 
kmg -v ling, 

gjram, Fig 
2 sonnections are 

an : Jting issoh le for ill 
.-- p to 1 '-_-.::. -_ :!:. ;: : : larger 
coils better : - Its .1 

adenf type :: inter- 
in which a separate magnet is 
I interi t the fdi 
v.- :-.:.-- \: ri ; : :, tloere are sev- 
eral other : ; the mercury 
commutator types, 
me better known tn 
: _::e ex- 
pi denced in coil operation. 



Automatic Time Switch 



This device can be used to either 

open or close the circuit at any desired 

time. An alarm clock is nrmlv fast- 

a wooden bracket and provided 

?mall wood or metal drum, A. 

I stened a : n ' . I. The 

od : the jord is tied :: the 

switch handle ; ~ f hat when the alarm 

r;es :f : - \ : : o_:l. : : riiei. :r 

ading on whethei the cord 

sed ova pulley C :r p'-Aley I). 




Will Open or Clos-e Circuit as D«sired 



POPULAR MECHANICS 



When the cord is passed oyer pulley 
shown in Rg. 1. the circuit will 

be closed when the alarm goes off, but 

patted over I» the circuit will 
nea. Pullej I ' is fastened to a 
of spring Bteel, E, which in op- 
eration i- bent, aa shown by the dotted 
lines, thus causing the Bwitch to snap 
open quickly and prevent forming an 
arc. Contributed by Douglas Boyer, 



on the cars are 5-cent ink bottles. 
Tbe engineer at the side of the loco- 
motive is a picture out of a magazine, 
and the picture of I ton. M. B. Cullum, 
.Mayor of Duluth, appears through the 
cab window. — Contributed by Chas. 
Rigdon, Plumbing Inspector, Duluth, 
Minn. 



A Neat Model Locomotive 



ng your description of a 
locomotive made oul of w 1. 1 here- 
with enclose a photograph of a loco- 
motive and tender complete made of 

52 in. in length including t< ader. 
Gasoline is u-< d for fuel supplied from 



Protection of Spring Lock 



After shutting the front door and 
hearing the Bpring leek snap into its, 
. most p. ople go off with a child- 
like faith in the safety of their goods 
and chattels. Bui the cold fact is that 
- scarcely any locking device 
which affords less protection than the 
ordinary spring lock. It is the sim- 
ple-! thing in the world for a sneak- 




Thc Locomotive Has a Speed of 6 Miles an Hour 



a small tank in the tender j the boiler is 
made of *'-in. seamless drawn brass 
tube with <>u>- 3-in. brass flue running 
the entire length of the boil< r. It is 

provided with steam brake- and -nam 

whistle, springs and equalizing lever. 
Cylinders 1 \ in. by --in. stroke. Drivers 

are ii in. in diameter. The locomotive 

will run on circular track with a Bpeed 

of about <"» miles per hour, the gauge 

of the track being •*> ', in. The whole 

locomotive and tender weighs about 87 

lb. and was made by the und< rsigned. 

H 1 picture was taken in a 

store window where the locomotive was 

put up for exhibition. The background 

of a photograph of a lake in 

cleverly arranged by the artist. 

who took the picture. The roadbed as 

well as the cars arc made up for the 

□ from magazines. The wheels 



thief to Blip a thin knife between the 
door-casing and the strip, push back 
the bolt, and walk in. 

Fortunately, it is equally easy to 
block that trick. Take a narrow piece 
of tin 3 or I in. long, bend it at right 
angles throughout its length, and tack 
it firmly in the angle between the 
casing ami strip, bo as to make it im- 
possible to reach the bolt without tear- 
1 the strip. 

Another way is to drive nails through 
the -trip at intervals of half an inch, 
enough to protect the bolt from 
tampering. 

♦ • ♦ 

A good imitation amber may be 
made of the following ingredients, 
melted carefully together: Pine rosin, 
1 part ; shellac, 2 parts ; colophony, 
15 parts. 



POPULAR MECHANICS 




How to Photograph on Apples 



- - 
a the sunny 
suggest 

:\ wh 
phot graphic 
_• man- 

o a 

ao with 

7-:. 
the paper and 

ring wl ite " ~ gg is th 

7; keej the rest 7 T5e apple 



• 
. "7th an openi 2 
jpposit the I are. The res 

phot graph was -wonderfully clear and 
beautiful, as appears In th - 

An autograph message may fc 
ten on thin paper and printed in the 
same way; also fern leaves Is .: 

ad ma] 



Novel Wireless System 

make plain 2 
- 

I have 
7: 

- - 1 : 2 - - : It is 

- that the ts - 1 aly need 

-:...-... [n Fig. 1 is s "• 

- - ■ . i Veell 

battery eonnecterl with two copper 

I ... Th 
are separate" piece of hard 

:77 ->: •: — :7. -1. 7 
In 7 _ -een duplies: 

insulated plates, connected with 
an ordinary telephone re 

1 can hear distinctly the 
----- sing ai 

openiru Fig 1 and I 

nt time 1 ?5all he 
7-r - ■.-;: - .- this systen: ; : :- ; . 
send wireless ges >vei long lis- 

— nti i / by Dudley H. 
7_ r_. New York. 



::==£= =m 3 =;.^.-£= 



; , I ;". 



::-: J : : . \!-j_£r:r=. 



-- = : =.«r= s.--: = 

TRANsnrrrmG station. 




~l.5=-; r =.-:r/i= 



3 



fS2- 



POPULAR MECHANICS 



A Home-Made Water Motor 



By Mrs. Paul S. Winter 



In the-e <lavs of modern improve- 
menta, mosl houses are i quipped with 
a washing-machine, and the question 
that arises in the mind of the house- 
holder i- how to furnish the power to 
run it economically. I referred tin- 
question to m) husband, with the re- 
.-11 It that he buill a motor which proved 
fai tor) that I prevailed 
upon him to rive the readi rs of this 

oe a deft ription 
of it. hoping it ma) Bolve 
ime question for 
them. 

\ motor <>f tl: 
will develop aboul h hp. 
with a water pressure of 
70 li.. The power devel- 
oped is correspondingly 

&fled u 

the i eeds or 

fall- below tin-. In the 
latter <ase the power 

may !"■ increaseo by 
using a smaller pulley. 
Figure l is the 
with one aide removed, 
-how ing the paddle-wheel 

in position : I'l.i:. 2 i- an 

end \.' shows 

one of the pa. Idles; 
ami Fig. ! show- the 

of shaping the paddles. 
the frame, several length 
ling •"■ in. wide by i 

ibly of hard w h 



of the frame. They are shown in Fig. 
S as GO. l'o not fasten these boards 
now, l.ut mark their position on the 
frame. Two short hoard- 1 in. wide 
by 1 in. thick I II H. Fig. 2) and an- 
other 1 in. by l{ m. ( I. Fig. 2) forma 
substantia] base. 

Cut the wheel from sheet iron ^ 
in. thick, VI in. in diameter. This 
can he done roughly with hammer and 
chisel ami then smoothed up on an 
emery wheel, after which cut 24 radial 
slot- ] in. deep on its ci rcn m fen nee 

by means of a hacksaw. On each side 




Details of Home-Made Water Wheel 



method 
T ake 

-i scant- 
in. thick 
are re- 



quired. Cut two <>t' them I ft. Ion-, j,, 
form the main BUpports of the frame, 
\.\. Fig. 1 : another. 'J ft. li in. long, 
for the top, li. I'll. 1 . 1 : another, ".'•'> in. 
to form the Blanting part. c. 
I _. l : ami another. I>. approximately 
l it., according to the -lant given C 
Alter Bailing her as Bhown 

in the illu-t ration, nail two short 
strips on each .-ide of the outlet, as at 
E, to keep the frame from spreading. 
Cut two pieces 30 in. long. Lay 

- of the frame with 
their center lines along the line V\-\ 
which i> 15 in. from the outside top 



of the wheel at the center fasten a 
rectangular piece of j-in. iron 3 by 4 
in. and secure it to the wheel by means 
of four rivets: after which drill a §-in. 
hole through the exact center of the 

wheel. 

Cut 24 pieces of 1/32-in. iron, 1£ 
by 2.1 in. These are the paddles. 
Shape (hem lev placing one end over a 
section of 1-in. pipe, and hammer bowl- 
-haped with the peen of a hammer, as 
shown in Fig. I. Then cut them into 
the shape shown in Fig. 3 and bend 
the tapered end in along the lines JJ, 
after which place them in the slots 
of the wheel and hend the sides over to 
damp the wheel. Drill J-in. holes 
through the wheel and sides of the pad- 
dles and rivet paddles in place. Next 
secure a g-in. steel shaft 12 in. long 



POPULAR MECHANICS 



63 



to the wheel about 8 in. from one 
end by means of a key. This is done 
by cutting a groove in the shaft and a 
corresponding groove in the wheel and 
fitting in a piece of metal in order to 
secure the wheel from turning inde- 
pendent of the shaft. Procure two col- 
lars or round pieces of brass i KK. 
with a f-in. hole through them, 
and fasten the shaft by means 

: set screws to prevent lit from 
moving lengthwise. 

1 1 fee the nozzle by taking a piece of 
£-in. galvanized pipe 3£ in. long and 
filling it with babbitt metal ; then drill 
a ^-in. k°l e through its 
this hole conical, tapering from ^ in. 
to a full 4 in. This is best done by 
using a square taper reamer. Then 
place the nozzle in the position shown 
in Fig. 1, which allows the stream of 
water to strike the buckets full in the 
center when they reach the position 
farthest to the right. 

the side pieces. GG. and drill 
a 1-in. hole through their sides cen- 
trally, and a ^-in. hole from the tops 
to the 1-in. holes. Fasten them in 
their proper position, with the wheel 
and shaft in place, the shaft project- 
ing through the holes just mentioned. 
Xow block the wheel: that is, fasten 
it by means of wedges or blocks of 
wood until the shaft is exactly in the 
center of the inch holes in the side 
pieces. Cut four discs of cardboard to 
slip over the shaft and large enough 
to cover the inch holes. Two of these 
are to be inside and two outside of 
the frames (one to bear against each 
side of each crosspieee). Fasten these 
to the crosspieces by means of tacks 
to hold them securely. Pour melted 
babbitt metal into the 4-in. hole to 
form the bearings. When it has 
cooled, remove the cardboard, take 
down the crosspieces. and drill a i-in. 
hole from the top of the crosspieces 
through the babbitt for an oil-hole. 

Secure sufficient sheet zinc to cover 
the sides of the frame. Cut the zinc 
to the same shape as the frame and 
let it extend down to the crosspieces 
EE. Tack one side on. (It is well to 
ta:k strips of heavy cloth, burlap will 



do, along the edges under the zinc to 
form a water-tight joint.) Fasten the 
crosspieee over the zinc in its proper 
position. Drill a hole through the 
zinc, using the hole in the crosspieee 
as a guide. Then put the wheel in a 
central position in the frame, tack the 
other side piece of zinc in place and 
put the other crosspieee in place. Place 
the two collars mentioned before on the 
shaft, and fasten so as to bear against 
the crosspieces, in order to prevent the 
wheel and shaft from moving sidewise. 
If the bearings are now oiled, the shaft 
should turn easily and smoothly. 
Fasten a pulley 4 or 6 in. in diameter 
to the longest arm of the shaft. 

Connect the nozzle to a water faucet 
by means of a piece of hose: place the 
outlet over a drain, and belt the motor 
direct to the washing-machine, sewing- 
machine, ice-cream freezer, drill press, 
dynamo or any other machinery re- 
quiring not more than i hp. 

- motor has been in use in our 
house for two years in all of the above 
ways, and has never once failed to give 
perfect satisfaction. It is obvious that, 
had the wheel and paddles been made 

--.it would be more durable, but 
as it would hi - several times as 

much, it is a question whether it would 
be more economical in the end. If 
sheet-iron is used a coat of heavy paint 
would prevent rust and therefore pro- 
long the life of the motor. The motor 
will soon pay for itself in the saving 
of laundry bills. We used to spend 
from 50 cents to $1 a month to have 
just my husband's overalls done at the 
laundry, but now I put them in the 
machine, start the motor, and leave 
them for an hour or so. At the end 
of this time they are perfectly clean, 
and I have noticed that they wear 
twice as long as when I sent them to 
the laundrv. 



A brilliant polish may be given to 
tarnished nickel by immersing in alco- 
hol and 2 per cent of sulphuric acid 
from 5 to 15 seconds. Take out. wash 
in running water, rinse in alcohnl, and 
rub drv with linen cloth. 



POPULAR MECHANICS 



Barrel Stave Hammock 



.urn ock made <>f band stares 
is more comfortable than one would 
think, considering the nature of the 

;! employed in making it. » I I 

smooth staves should be selected .for 
this purpose, and to go bo 

a little trouble a thorough sandpaper- 
ing will make a greal improvement 

[f circle- oul of each atave, aa 

shown at A.\. and paai ropea around 

• i: When finished 

... il] then be supported by 

four ropea at each end, which allows 

the u-.' of small • inch as 

- Lin< b. A hammock of this kind 



them up, and plane off about -fa in. on 
the upper left hand corner and lower 
righi hand corner, as in Fig. 2. 

\c\t restore all the cards to one 
pack, taking care to have the first card 
red, the next black, and bo on, every 




Cheap and Comfortable 

may be lefl out in the rain without in- 
jury.— Contributed by 11. Q. II., 8t 

. M". 



rusl may be taken oul of mus- 
lin «.r linen goods by wetting with 
lemon juice and -alt and exposing to 
sunlight. If at first you don't succeed, 
ain. 

A Mechanical Card Trick 

















A 






A 






♦ 






* 






V 






X 






Fig.l 






F/g.2 





illo* ing mechanical card trick 
to prepare and simple to per- 
form : 

■■• a n< w deck, and divide 
ir into two pile8, one containing the 
red cards' and the other the black ones, 
all card- facing the -an e way. Take 
. square them np and place 
in a vise. Then, with a plane, plane off 
the upper right hand coiner and lower 
left hand corner, aa in Fig. 1, about 
T^in. 

Then take the black cards, square 



Mechanical Card Trick 

alternate card being the -ante color. 

Bend the pack bo ae to give some Bpring 
to the cards and by holding one thumb 

on the upper left hand corner all the 
cards will appear red to the audit nee ; 
place thumb in the center at top of pack 
ami they will appear mixi 'I. P( d ami 
black : with thumb on upper right hand 
corner all card- appear black. You 

can display either color called for. — 

Contributed by Ralph Gingrich, Chi- 

cago. 

♦ * ♦ 

To Explode Powder with Electricity 

A l-in. hole wa- bored in the center 
- n. square block. Two finishing 

nail- were dri\en 
mown in 
the sketch. 
ere con- 
nected to termi- 
nals of an induc- 
tion coil. After 

everything w a s 
ready the pow- 
der was poured 
in the bole ami a board weighted with 
rocks placed over the block. When the 
button i- pre— ed or the circuit closed 
in -nine other way the discharge occurs. 
The distance between the nail points — 
which must be bright and clean — should 
be ju-t enough to give a good, fat 
spark. — Contributed by Geo. W. Fry, 
San Jose, Cal. 




POPULAR MECHANICS 



e^fc Amateur Mechanics S* 



How to Make "Freak" Photographs Electric Blue Light Experiment 




The "freak" pictures of well-known 
people which were nsed by the leading 
dailies recently made ev- 
erybody wonder how the 
distorted photograr 

.- . -" - --. . .- - 1 
Craft gives the s e 
which proves to be easy of 
execution. The distortion 
is accomplished by the use 
of prisms, as folk - 8 - 
cure from an optician or 
leaded glass establishment, two glass 
. slightlv wider than the lens 
mount. The flatter they are the less 
they will distort; about 20 s is a satis- 
factory angle. Secure them as shown by 
sectional sketch, using straw board and 
black paper. Then make a ring to fit 
over the lens mount and connect it with 
the prisms in such a way as to exclude 
all light from the camera except that 
which passes through the face of the 
prisms. The inner surface of this hood 
must be dull black. The paper which 
comes around plates answers nicely. If 
the ring which slips over the lens mount 
is lined with black velvet, it will exclude 
all light and hold firmly to the mount. 

Place over lens, stop down well after 



Take a jump-spark coil and connect it 
up with a battery and start the vibrator. 
Then take one 
outlet wire. B, 
and connect to 
one side of a 
2-cp. electric 
lamp and the 

' -Z L'r' ~'.: :. 

B, hold in one 
hand and press all fingers of the other 
hand on globe at point A. A bright, 
blue light will come from the wires in 
the lamp to the surface of the globe 
where the fingers touch. Xo shock will 
be perceptible. — Contributed by J. H. 
Spade.. Ave., Altoona, Pa. 




How to Make a Music Cabinet 



A neat music cabinet can be made as 
shown in the accompanying sketch : 

Each side, AA, Fig. 1, is cut from a 
board about 36 in. in length and 16 in. 
wide. Both are alike and can be cut 
from same pattern. As the front legs 
curve out a little the main body of the 
boards. AA, should be 15 in. wide. The 
back. B. should be about 22 in. long by 
l ; : :r_. ~ : ~z iz ': ~-z in ' -:-— --. r_ -: ~->- AA. 



i : : '." - ._ . ~ . t:t'. C"~i "is f'T 8.H" i: :-~r-r. '/:: :i^ t:t . . . Li in. _ . ~ _" iz . '--'_ in. 



ib 




asg» 




J- 
















> 




/ y^- 


">.'•- ^v 


Jjz^ 




/^ 




= 












5TRAW 


BOARD 




-':■:? z:z - : : : 



"The Distortion Is Accomplished by the Use of 



POPULAR MECHANICS 



The bottom must be th< 

ip and l'-\\ in. will.-. 

I ». i an l>»- made pai 

e, 16 in. \\ ide and 




How to Make a M 



■ 

rdfl that will i 

irk. 

own in 
from } in. material. 
■ . long, from 
a atrip 

. in. « at in i 

I uli. A 
A ill g|\e 

• Bhelves 
i lovable two pla< i - i an I"- made 



Mow to Make a Three-Way Cock for 
Small Model Work 



In making modelfl <>f machines it i~ 

fur a 'A or I- 

: 1 V e <m 

I'm make 
re a pet 
cock and <lrill 
and t a p h <» 1 e 
thro u g li. a - 
shown in the 
rut. If for :'- 
way. drill in 
only to tin- open- 
ing air* I l-way. 
drill through the entire case and valve. 
Be bui live B turned so as 




t<> drill at right angles to the- opening 

through it. After drilling, remove the 

valve and remove the bur with a piece 

i : . paper ami replai e ready for 

work. 

How to Transmit Phonograph Music 
to a Distance 



An interesting experiment, and one 
calculated to mystify any one nut in 
s to transmit the music or 
from a phonograph to another 
part hi' the bouse "i- even a greater dis- 
For an outdoor summer party 
the music can he made t<> come from a 
bush, or tree, or from a bed of flowers. 
Tin- apparatus i> not difficult to con- 
struct. 
'I'll-- cut showe the arrangement Pro- 




cure a long distance telephone transmit- 
'. including the mouthpiece, ami 
Fasten it to the reproducer of the pho- 
Dograph. Also a watch case receiver, K. 
which fasten to the horn. These parts 

<an he purchased from any electrical 

supply house. Connect two win- to the 
transmitter, running one direct to the 

receiver, ami the other to the Lattery. 
thence to a Bwitch, S, and then to the 
receivi r. The more batteries u«-<\ the 
loud.r will be the sound produced by 
the horn, hut avoid using too much bat- 
tery or the receiver i- apt to heat. — ( lon- 
tributed by Win. J. Farley, dr., Cam- 
den, \. T 

The Russian government is building 
sevena] cars for transporting live fish 
which are to he planted in Western Si- 
beria. 



POPULAR MECHANICS 



To Make a Negative Without 
Plate or Film 



The accompanying illustration is a 
reproduction of a photograph print ob- 
tained from a nega- 
tive made of de- 
veloping or g a s 
light paper which 
was used in the 
plate holder instead 
of a plate or film. 
The time given to 
make this exposure 
was one minute. 
The bath used in 
developing and fix- 
ing is the same as 
on prints. 
"When through the 
qs, washed and dried, it is then 
printed in contact the same as a film, 
only i: - nger time in print- 

ing. — Contributed by Charles W. Fank- 
boner, Grand Rapids. Mich. 

How to Make a Hollow Ball 




The illustration shows a hollow ball. 
6 in. diameter, the shell being about 
1J in. thick. It contains 263 pieces 
of hardwood, fit- 
ted perfectly with 
glue. Twenty-five 
kinds of wood 
were used. A 
6-in. ball of fir 
was first turned 
and a chuck made 
to hold the ball. 
Holes were then 
bored to a depth 
of 3 in. (to the 
center of the ball ) 
and wooden plugs were inserted just 
W in. "When the entire surface of the 
ball had been thus bored and plugged, 
I had a ball 6 in. diameter with a 
\\ in. shell and a 3-in. diameter hollow 
within. Each plug was turned out sep- 



arately and the hole made to fit the 
plug. Some of the plugs were made up 
of different kinds of wood in different 
ways and glued together before being 
turned. 

The stand contains 19 pieces of wood 
which were first cut in triangles and 
glued in the form of a hexagon. Two 
of these layers were glued and turned 




on a face plate to form the bowl, the 
other layer was turned to form the 
base, while the column is one piece of 
walnut. The task required consider- 
able time and patience. — Contributed 
by C. E. Mallory, University of Wash- 
ington, Seattle, "Wash. 



A Musical Windmill 



Make two wheels out of tin, which 
may be of any size, but wheel A must 
be larger than wheel B. On wheel A 
fasten two pieces of wood, C, to cross 
in the center, 
and place a bell 
on the four ends, 
as shown. The 
smaller wheel, 
B, must be sep- 
arated from the 
other with a 
round piece of 
wood or an old 
spool. Tie four buttons with split 
rings to the smaller wheel, B. The 
blades on the wheels should be bent 
opposite on one wheel from the others 
so as to make the wheels turn in dif- 
ferent directions. "When turning the 
buttons will strike the bells and make 
them ring constantly. 




POPULAR MECHANICS 



How to Build a Grape Arbor 



ide of white pine, 
ten, will 

l-in. 




■t- 



of post A mill run through first hole 
uinl over in first notch t<> back of board 
and thru through b< cond hole and over 
second notch and bo od until E is 
reached, where the other end of wire is 
fastened. Connect Bwitch to posi B. — 
Contributed by Edmund Kuhn, Jr., 
1 angi . \. .'. 

Novel Mouse Trap 




(ir«pc \rl..,r Irclhi 

■ ■ d and 
a brick placed under each end. The 
■ 

1 I to the 

jof a nail through a hole In 

- driven into the ground, which 

Q, \. I ' 

\ Battery Kncostat 



A piece "f an old bicycle tire and a 

■ nit jar arc the only materials 

required for making tin- trap. Tush 
one end of the tire in the hole, being 
sure that there ie a space left at the end 
so that the mice can gel in. Then bend 

the other end dnw n into a fruit jar or 
other glase jar. Bait may he plai ed in 
the jar it' desired, although tin- i- not. 



•id :. in. wide 

.n. apart in a Semi- 
. i r c I • ■ 

from the bot- 
tom and cut 

- 
ppond w i t h 

From b 

Bwitcl 

i t h a 
knob - 

Nails I o t 

• I »l >. 
Two binding-posts are placed in board 

B With about 9 it. of line 
inm wire attach one ■ od to the bottom 




Contributed bj Geo. <i. 
McVicker, North Bend, Neb. 

One-Wire Telegraph Line 



The accompanying wiring diagram 
Bhows a telegraph system that requires 
no Bwitchee and can he operated with 
open-circuit batteries on a one-wire 



Battery 



jh 



1- 



Scundei 



Battery 

BrL 



V 



Diagram of One-Wire Line 



POPULAR MECHANICS 



71 



line with ground connections at each 
end. Any telegraph set in which the 
able contact can be con- 
up in this way. — Contributed 
by R. A. Brown. Fairport, N. Y. 



How to Make a Rotary Pump 



-.-••■ r r -,- r - f :rf •;■■■:.- 



A simple rotary pump is constructed 
on the principle of creating a vacuum 
in a rubber tube and so causing water 
to rise to fill the vacuum. Figs. 3. 4 
and 5 show all the parts needed, ex- 
cepting the crank and tubing. The 
dimensions and description given are 
for a minimum pump, 
but a larger one could 
be built in propor- 
tion. 

Through the cen- 
ter of a block of wood 
4 in. square and 
in. thick (A, Figs. 1, 
2 and 3) saw a cir- 
cular opening 2 
in diameter. On each 
side of this block cut 
a larger circle 
in diameter, having 
the same center as 
the first circle (Fig. 
3). Cut the last cir- 
cles only J 4 in. deep, 
leaving the first cir- 
cle in the form of a 
ridge or track 
wide, against which 
the rubber tubing, E, 
is compressed by 
wheels. Bore two l i- 
in. holes THH. Tig. 
1) from the outside 
of the block to the 
edge of the inner cir- 
cle. Put the rubber 
tube, E, through one 
of these holes, pass it 
around the track and 
out through the other 
hole. Notice the break (S) in the 
track ; this is necessary in order to 
place in position the piece holding the 
wheels. 



Figure 4 shows the wheel-holder, 
B. Make it of hard wood 3;$ in. long, 
1 in. wide and a little less than 
thick, so that it will run free between 
the sides (Fig. 5; when they are 
placed. Cut two grooves, one in 
each end, 1 in. deep and l /z in. wide. 
In these grooves place wheels, CC, to 
turn on pins of stout wire. These 
wheels should be f< in. in diameter. 
When placed in the holder their cen- 
ters must be exactly 2 in. apart, or so 
arranged that the distance between the 
edge of the wheels and the track 1 K. 
Fig. 1 ) is equal to the thickness of the 
tubing when pressed flat. If the 




Details of Rotary Pump 

wheels fit too tight, they will bind; if 
too loose, they will let the air through. 
Bore a hole through the middle of 
the wheel-holder and insert the crank- 



I'Ul'l I.AK MECHANICS 



pin, D, which should be about ' i in. 
in diameter. The crankpin should fit 
tight ; if i brad 

slipping. 
In il .. hole in 

tet of the crankpin t<> run in 
. \'..w put all tl 
gether, as shown in the illustration. 
i curely 
until you have tried the devi 
re it will run smoothl) 
ink a bent ; ut wire 

or a nail will sei i small 

: 
• 

i I to the rim 

of tin The 

drive 

handling the pumj should 



How to Make a Small Medical 
Induction Coil 



The coil to be described is 3| in., 
full length of iron core, and :'» in. in 
diameter, 

ire a bundle of small iron win 1 . 

Bay \ in. in diameter, and cut it .*U in. 

ad neatly with coarse thread 

and file the ends smooth (Fig. 1 ). This 

done, make two irood ends, 1 1 bj l { in. 

in. (hick, and .arui-h. Bore 

n the . enter of each bo the tore- 

will tit in snugly and leave aboul 1 in. 

• ing from ea . 1). 

After finishing the core, Bhellac two 

of thick paper over it between 

• this dry thoroughly. Wind 

two layers of bell magnet wire over 

this, allowing several inches of free \\ ire 

to come through a hole in the i nd. 



•MNALS WIRE NO. 31 TO HOLDERS 

J L. 




/-.-.: v ■'•:■'.:. 



TERMINALS NO. 24 
OR BELL MAGNET WIRE 



BATTERY 






S 



ZW HEAD 



PLATINUM 



FiP.2 



Medical Induction Coll 



pump, fill the tube with 
• end of the 

tube in lake a 

i f the end of a clay pi) 
for the other end Then 

turn the crank fr.»m left t«» right. The 
of the 

uuin which is im- 

ith water. B< fore 

the fir-t wh< the tube at the 

other wheel has reached the 

. this time | ng the 

light up by the fir-t 

wheel. It the motion <>f the wheels 

liar, the pump will 

tubing, 

: > all the expense 

1 Contributed by 1 tan II. 
Hubbard, [dana, Kan. 



with paper and Bhellac as before, 

Wind about i in. of fine wire, such 

on telephone generators, around 

. leaving long terminals. Soak 

the whole In melted paraffine and Let 

bind tightly with Mack silk. 

The vibrator is made of a piece of 

thin tin tn which is soldered the head 

of an iron Bcrew and on the oth< r Bide 

a small piece of platinum, which can 

be taken from an old elo trie bell 

irse, a regulator must be had 
for the vibrator; this can be accom- 
plished by bending a Btoul piece of cop- 
per wire as Bhown. The connections 
and tl ■ etting up are shown 

in the figures. — Contributed by J. T. 
I.'.. Washington, I). C. 



POPULAR MECHANICS 



How to Make a Small Electric 
Furnace 



Take a block of wood and shape into 
a core. One like a loaf of bread, and 
about that bl ..irably. Wrap 

a layer of asbestos around it an . 





J IIH V; -„:-.. - 




n 


<P 




< s;. 


! 








:■' 




J 1 



or Xo. 14 wire, connecting lamp recep- 
tacles, B B. and switch. C, in paral- 
lel. Connect these three to switch, D, 
in series with binding-post, F, the ter- 
minal of the coil. Place 16-cp. lights 
in the receptacles and connect the fuses 
with a 110-volt lighting circuit. The 
apparatus is now ready for operation. 
Turn on switch, D, and the lamps, 
while C is open. The coil will com- 
mence to become warm, soon drying 
out the plaster-of-paris. To obtain 
more heat open one lamp, and to ob- 
tain still more open the other and close 
switch, C. — Contributed by Eugene 
Tuttlcs. Jr.. Newark, Ohio. 

How to Make a Fire Screen 



Electric Furnace 

this with a thin layer of plaster-of- 
paris. "When the plaster is nearly dry 
wind a coil of Xo. 36 wire around it, 
taking care that the wire does not 
touch itself anywhere. Put another 
course of plaster-of-paris on this, and 
again wind the wire around it. Con- 
tinue the process of alternate layers of 
plaster and wire until 500 ft. or more 
of the latter has been used, leaving 
about 10 in. at each end for terminals. 
set the whole core away to dry. 

For a base use a pine board 
by 12 in. by 1 in. Bore four holes 
at one end for binding-posts, as indi- 
cated by E E. Connect the holes in 
pairs by ordinary house fuse wire. At 
one side secure two receptacles, B B, 
and one single post switch, C. Place 
another switch at I and another bind- 
ing-post at F. The oven is now ready 
to be connected. 

Withdraw the wooden core from the 
coils of wire and secure the latter by 
bands of tin to the board. Connect 
the ends of the wire to binding-posts 
E and F. as shown. From the other 
set of binding-posts, E, run a Xo. 12 



A s reen which will not interfere 
with the radiation of the heat from 
the fire, and will keep skirts and chil- 
dren safe can be made at little expense 
out of some strap iron. The screen 
which is shown in Fig. 1, stands 20 in. 
high from the base to the top cross- 
piece and is made of f by \ in. and \ 
by \ in. iron. The top and bottom 
- marked AA. Fig. 1, are f by \ 
in. and are 30 in. long, bent at an angle 
', in. from each end, 




Made of Strap Iron 






POPULAR MECHANICS 



of in.il i .1 . I n shaping the 

■ 
rrard the fin 

■.■!• in in 

i .. h end, 

I 3 in. 

Take 

from 



each end, and mark for a hole, and 3| 
in. on each Bide mark again and '.'>\ in. 
beyond each of these two, mark again. 
ii. from ili«' bottom 
and 2 in. from the t « • | » ami make rivet 

ind rivel them to i : 
\\. I 

Cut >i\ pieces, \',\ in. long and 

punch holes to tit and rivel onto the re- 

tnaining holes in cross bars, AA, Fig. 1. 

( lean it up and gn • of black 

• >r dead black. 



How to Make a Simple Water Rheostat 



nrrenl of 1 1<"> voltage it will be 

or w ten 



• 



ght, which will hold 
al. Ea< Ii jar to be oiled 
1 parts water to l part sulphuric 



MOTOR 




WIRES A TO BE RUBBER COVERED 



N\ Irlntf llan for Water Rheostat 



• ■ii the 

im bat- 
large, 
lint if you intend 



acid. .' ;M a r<>w in some 

. onvenient place ou1 of the way. 
\.-\t cut out eight 1 copper or brass 

two tor cadi jar. Their size 

also depends on the voltage. Tl 



POPULAR MECHANICS 



that are placed in the lower part of the 
• connected with a rubber cov- 
re extending a little above the 
top of the jar. 

To wire the apparatus, refer to the 
;nd you will see that jar Xo. 1 
is connected to point Xo. 1 on switch : 
I so on until all is 
complete and we have one remaining 
point on switch. Above the jars place 
a wire to suspend the other or top discs 
in the solution. This wire is also con- 
nected to one terminal on the motor 
and to remaining point on switch. The 
arm of the switch is connected to one 
terminal of battery, or source of cur- 
rent, and the other terminal connected 
direct to remaining terminal of motor. 

Put arm of switch on point 
and lower one of the top discs in jar 
Xo. 1 and make contact with wire above 
The current then will flow 
through the motor. The speed for each 
point can be determined by lowering 
top discs in jars. The top disc in jar 
: down than in Xo. 1 and 
so on for Xo. 3 a: he con- 

nection between point Xo. 5 or. 
direct to wire across jars, gives full 
current and full speed. — Contributed 
orth. Pa. 



Enlarging with a Hand Camera 



Every person that owns a hand cam- 
era has some pictures he would like 
enlarged. It is nor necessary to have 
a large camera to do this, as the proc- 
gly si mple to make large 
pictures from small negatives with the 
same hand camera. 

A room from which all light may 
be excluded and a win- 
dow through which the 
light can enter without 
obstruction from trees or 
- ::.: "."' '.::! \^— ~r.~':. :. 
shelf to hold the camera 
and a table with an up- 
right drawing board at- 
tached, complete the ar- 
rangement. The back is 
taken out of the camera 
and fitted close against 



the back of the shelf, which must 
be provided with a hole the 
size and shape as the opei 
the back of the camera. 
ative used to make the enlarged 
print is placed in the shelf at A. 
1. The rays of the clear, unobs": 
light strike the mirror. B, and 
through the negative. A, through the 
the camera and on the board, 
l Fig. 2. The wind", 
be darkened all around the shelf. 

After placing the negative and fo- 
cusing the lens for a clear image on 
the board, the shutter is set and a bro- 
mide paper is placed on the board. The 
paper is exposed, developed an ; 
by the directions that are enclosed in 
the package of bromide papers. 
» ♦ -♦ 

Gasoline Burner for Model Work 

When making a small model traction 
engine or a locomotive the question 
What shall the fuel be? 



i 


—r-r- ■ 




=^=^- <*&£,* 




^~~ 


ru _^ - - _ 



you have decided to use _ 
a suitable bun 

of brass tubing about 3 in. in diam- 
eter and 6 in. long with 
on both ends and fitted with a filling 
plug and a bicycle valve makes a good 
gasoline supply tank 
_ 

the tank 
sure which forces the gasoline to the 
burner. 




POPULAR MECHANICS 



The burner is made from a piece of 
-how ii in the illus- 
tration, ] in. in diameter and Z\ in. 
long, irhicfa is plugged up at both ends, 

one end being drilled and rea d out 

a, Three rows of boles ,', ; in. 
in diameter are drilled in the brass 
tube. < me row is drilled to come di- 
rectly "ii top and the other two al aboul 
mi the vertical. It is then fitted 
B, means of the 

C, 1 | \ of i-in. 

copper pipe, 1\ is t h«n coiled around 
the brs i, which forms the 

vaporizing ooiL This * « » i I should have 
■ diameter of only 1 in. One end of 
the copper tube is benl around bo it 
will jMiint directly into the reamed 
out hole in the end of the brass tube, 
A. A nipple, N. i- made by drilling 
a. hole half-way through a 



to lit tin' sides 

at the p 1 a c c a 
where fcney arc 
n a M t e d. The 

11 u iii li e r o f 

shelve- ran 1m 1 

varied and to 

suit the siae of 

the dishes. < 'up 

hooks are placed on top and bottom 

shrives, it i< hung on the wall the 

same as a picture from the moulding. 

ributed by F. B. Emig, Santa 

Clara. Cal. 





- and tapping to acrew < 
end of the i-in. copp r \ 

hole is then drilled through the re- 
maining part of the nipple. The other 
end of the copper tube is connected to 
the supply tank. The distance between 
the nipple, N. and the ends of the 
\. Bhould be only ,';., of an inch. 
1 .' .-how.- the end \ iei . 



How to Make a Cup and Saucer Rack 



A Window Conservatory 
Daring the winter months, where 

house plants are kept in the home, it 

is alws »b l)"\\ to arrange 

-■> they can gel the ne© 

lighl without occupying 
too much room. 

The sketch -hows how 

B neat window con 

tory may be made at 
small ro-t that ran be fas- 
tened on the house jusl 
covering a window, which 
w ill pn»\ ide a fine place 

for the plants. The 

frame ( Fig. 2 i is made 
of aboul '.' by ''-in. ma- 
terial framed together as 
-hown in Pig. 3. This 
frame should be made 
with the three openings 
thai a four-paned 
Bash, Buch as osed for a storm 
window, will fit nicely in them. If 
the four vertical pines thai arc .-hown 
in Pig. 2 are dressed to the right angle, 
thru it will be easy to put on the finish- 
ing corner hoards that hold the sash. 

The top. as well as the bottom, is con- 
structed with two small pieces like the 

rafters, on which is nailed the sheath- 
ing hoards and then the shingles on 
top and the finishing boards on the 
bottom. 



The rack is made of any kind of 
w 1 suitable, of whi b sides, A. are 

cut ju-t alike or from one pattern. 
The shelves are made in various widths 



Deposits of copper netting $10 a ton 
were recently discovered in southwest 

Africa. 



POPULAR MECHANICS 



HOW TO MAKE SILHOUETTES 




Photography in all branches is truly 
a most absorbing occupation. Each of 
us who has a camera is constantly :-::- 
penmen ting, and 
one of us 
is delighted 
when something 
new is suggested 
for such experi- 
ments. 

To use a cam- 
era in making 
silhouettes select 
a window facing 
north if possible, 
or if used only 
at time; 
the sun is not on 
it. any window will Photo- 

graphic Times. Baise the window 
shade half way, remove any white cur- 
ere may be, and in the center 
of the lower pane of glass paste by the 
four corners a sheet of tissue paper 
that is perfectly smooth and quite 
thick, as shown in the sketch at B. 
Darken the rest of the window, shut- 
ting out all light from above and the 
sides. 

Place a chair so that 
after being seated the 
head of the subject will 
come before the center of 
the tissue paper, and 
near to it as possible, and 
when looking straight be- 
fore him his face will be 
in clear profile to the 
camera. 

other windows in the 
room. Focus the camera 



Correct exposure depends, of course, 
on the lens, light and the plate. But 
remember that a black and white nega- 
tive is wanted with as little detail in 
the features as possible. The best plate 
to use is a very slow one, or what is 
called a process plate. 

In developing get all possible density 
in the high lights, without detail in the 
face, and without fog. Printing is best 
done on contrasty development paper 
with developer not too strong. 

The ideal silhouette print is a per- 
fectly black profile on a white ground. 
With a piece of black paper, any shape 
in stopping off print may be made as 
shown at C in the sketch. 



HOW TO CROSS A STREAM ON 
A LOG 



When crossing a water course on a 
fence rail or small log, do not face up 
or down the stream and walk side- 
zjt a wetting is the inevitable 
result. Instead, fix the eye on the 
opposite shore and walk 




ong ex- forward. Then ii 

set may will fall with oa 

circling the bridg 



POPULAR MECHANICS 



A HOME-MADE ACETYLENE GAS 
GENERATOR 



HOME-MADE DISC RECORD 
CABINET 




A simple acetylene gas generator 
used by myself for several years when 
out. on camping 
trips was made 
of a galvanized 
iron tank, with- 
out a head, 18 
in. in diameter 
and 30 in. deep, 
B, as shown in 
the sketch. An- 
other tank, A, 
is made the 
same depth as 
B, but its di- 
ametei is a little smaller, so that 
Inverted it will just slip easily into 
the tank B. In the bottom, or rather 
the top now, of tank A is cut a hole 
and a little can. I ), is fitted in it and 
soldered. On top and over can D is 
soldered a large tin can screw. A rub- 
ber washer is fitted on this so that 
when the screw top, E, is turned on 
\\, the joint will he gas-tight. Another 
can, (', which will just slip inside of 
the little can, is perforated with a num- 
ber of holes. This can (' is filled about 
half full of broken pieces of carbide 
and then placed in the little can D. 
A gaa cock, H, is soldered on to tank 
A, as is shown, from which the gas may 
he taken through a rubber tube. Fill 
tank B with water and set tank A 
into it. This will cause some air to 
he inclosed, which can be released by 
leaving the cock open until tank A 
settles down to the point where the 
water will begin to run in the perfora- 
tions of the little tank. The water 
then comes in contact with the carbide 
and forms gas, which expands and stops 
the lowering of tank A. Then the 
cock must be closed and tubing at- 
tached. It is dangerous to attempt to 
strike a match to light a jet or the end 
of the cock while air is escaping and 
just as the first gas is being made. 
Wait until the tank is well raised up 
before doing this. — Contributed by 
James E. Noble, Toronto, Ont 



Select some boards that have a nice 
grain that are about 1 in. thick and 
12 in. wide. Cut the end pieces each 
36 in. long and trim down the edges so 
as to make them llf in. wide. The 
top board is made 28 in. long and full 
12 in. wide. The three shelves are cut 
25 in. long and the edges trimmed so 
they will be llf in. wide. The dis- 
tance between the bottom of the top 
board and the top of the first shelf 
should be 3 in. Two drawers are fitted 
in this space as shown in Pig. 1. A 
series of grooves are cut ^ in. wide, 
| in. deep and f in. apart on one side 
of the top and bottom shelves, as shown 
in Fig. 2, and on both sides of the mid- 
dle shelf. The shelves should be spaced 
9f in. for 10-in. records and 5f in. for 
6-in. records. A neat scroll design is 




Holds 32 Records 



cut from a board 25 in. long to fill up 
and finish the space below the bottom 
shelf. — Contributed by H. E. Mangold, 
Compton, Cal. 

HOME-MADE POTTERY KILN 



A small kiln for baking clay figures 
may be built at a cost of $1. The fol- 
lowing shows the general plan of such 
a kiln which has stood the test of 200 
firings, and which is good for any work 
requiring less than 1400° C. 

Get an iron pail about 1 ft. high 
by 1 ft. across, with a cover. Any old 
pail which is thick enough will do, 
while a new one will cost, about 80 



POPULAR MECHANICS 




Home=Made Pottery Kiln 

cents. In the bottom of this cut a 
2-in. round hole and close it with a 
cork or "wood plug. A. Fig. 1, which 
shall project at least 2 in. inside the 
pail. Make a cylindrical core of wood, 
B, Fig. 1. 8 in! long and 8 in. across. 
Make a mixture of clay, 60% ; sand. 
15 c c : and graphite, "25%, kneading 
thoroughly in water to a good molding 
consistency. Line the pail, bottom and 
si r ; . -rith heavy paper and cover the 
core with same. Xow pack the bottom 
of the pail thoroughly with a 2-in. 
layer of the clay mixture, and on it 
set the paper-wrapped core, carefully 
centering it. The 2 in. of space 
between the core and the sides of the 
pail all around is to be filled with clay, 
l. as is shown in the sketch, using a 
little at a time and packing it very 
tight. In like manner make the cover 
of the kiln, cutting the hole a little 
smaller, about 1 in. At the edge or 
rim of the cover encircle a "2-in. strip 
of sheet iron, E, Fig. 2, to hold the 
clay mixture, C. Set aside for a few 
lays Tintil well dried. 

While these are drying you can be 
m aking a muffle, if there is to be any 
glazing done. This is a clay cylinder 
(Fig. 3) with false top and bottom, in 
which the pottery to be glazed is pro- 
tected from any smoke or dust. It 
is placed inside the kiln, setting on 
any convenient blocks which will place 
it midway. The walls of the muffle 
should be about ^ in. thick, and the 
dimensions should allow at least 1 in. 
of space all around for the passage of 
heat between it and the walls of the 
kiln- By the time the clay of the kiln 



is well dried, it will be found that it 
has all shrunk away from the iron 
about f in. After removing all the 
paper, pack this space — top, bottom and 
sides — with moist ground asbestos. If 
the cover of the pail has no rim, it 
may be fastened to the asbestos and 
clay lining by punching a few holes, 
- _• wire nails through and clinch- 
ing them. Fit all the parts together 
snugly, take out the plugs in the top 
and bottom, and your kiln is ready for 
business. The handle of the pail will 
be convenient for moving it about, and 
it can be set on three bricks or some 
more elaborate support, as dictated by 
fancy and expense. 

The temperature required for bak- 
ing earthenware is 1250°-1310 c C: 
hotel china, 1330 = : hard porcelain, 
1390°-m0°. These temperatures 
cannot be obtained in the above kiln by 
means of the ordinary Bunsen burner. 
It will be necessary either to buy thb 
largest size Bunsen, or make one your- 
self, if you have the materials. If you 
can get a cone which can be screwed 
into an inch pipe, file the opening of 
the cone to ^ in. diameter, and jacket 
the whole with a 2^-in. pipe. The 
flame end of this burner tube should 
be about 4^ in. above the cone opening 
and should be covered with gauze to 
prevent flame from snapping back. 
When lighted, the point of the blue 
flame, which is the hottest part, should 
be just in the hole in the bottom of 
the kiln . Such a burner will be cheap- 
ly made and will furnish a kiln tem- 
perature of 11:00% but it will burn a 
great deal of gas. 

A plumbers torch of medium size 
will cost more in the beginning, but 
will be cheaper in operation. What- 
ever burner is used, the firing should 
be gradual, and with especial caution 
the first time. By experiment you will 
find that a higher temperature is ob- 
tained by placing a 1-in. pip: 
long over the lid hole as a chimney. 
It would be still more effective to get 
another iron pail, 2 in. wider than the 
kiln, and get a down draft by inverting 
it over the kiln at whatever height 
proves most suitable. — G. L. W. 



POPULAR MECHANICS 



HOW TO MAKE A PANTOGRAPH 



Secure four pieces of wood, from 
which cut and dress down to T \ in. by 
f in.; make two of them 31 in. long 
and the other two 24 in. long. These 
pieces of wood may be of any material, 
but it is best to make them of some 
hard wood. The "screw" in the sketch 
is a screw-eye long enough to pass 
through the arm and an old silk spool. 
This will keep the arms up from the 
board or table so as to allow a point 
at t racer point and pencil to be a little 
above the work. At tracer point a 
round-headed brass wood screw is used 
which is filed to a point and slightly 
rounding so it will not scratch. A lead 
pencil is sharpened and fitted in a hole 
marked "pencil." At point marked 
"roller" a screw-eye is put in from un- 
derneath to allow a rounding edge for 
this point to rest. The small holes on 
all arms an^ marked on the left from 
1^ to 6 and on the right from 6 to 
l|. When matched and clamped with 
a screw-eye will enlarge sketch or pat- 
tern from tracer point to the size of 
holes that arc numbered in the semi- 
circle. If holes marked l.\ on left are 
ma I el ied and holes l. 1 ,- on right are 
matched then it will increase the size 
of the drawing 1$. If No. 6 on the 













LFtoller 


6 — 
s — 








<*- 








-4 — 
-3K 








-i*-? 








r 3 ^ 








sj% 


h 


<o 






M 






A*T 






*"5 


"V\ £ 






'? 




\7 




♦j/ 




*f 


2 




L^y 


**t. 




,J?T? 










-35- 

- 4- 

- 5 ' 






<VV7 


-*- 




hi 




" 6 7 














>crew/ 






r Tracer jPoint 


\0 
















Rsncil 



left and No. 6 on the right are matched 
then the increase will be 6 times. The 
distance the holes are made one from 
the other is shown with the figures and 
inch marks. — Contributed by E. W. 
Bowen, Denver, Colo. 



CIRCUIT BREAKER FOR INDUC- 
TION COILS 



Amateurs building induction coils 
are generally bothered by the vibrator 
contacts blackening, thus giving a 



r-^drfjj 




Home-Mad* Pantograph 



Interrupter for Induction Coil 

high resistance contact, whenever there 
is any connection made at all. This 
trouble may be done away with by de- 
parting from the old single contact 
vibrator and using one with self-clean- 
ing contacts as shown. An old bell 
magnet is rewound full of No. 26 
double cotton-covered wire and is 
mounted upon one end of a piece of 
thin sheet iron 1 in. by 5 in. as per 
sketch. To the other end of the strip 
of iron is soldered a piece of brass 
1-64 in. by \ in. by 2 in., on each end 
of which has been soldered a patch of 
platinum foil % in. square. 

The whole is connected up and 
mounted on a baseboard as per sketch, 
the contact posts being of ■£$ in. by £ 
in. brass, bent into shape and provided 
with platinum tipped thumh screws. 
The advantage of this style of an in- 
terrupter is that at each stroke there is 
a wiping effect at the heavy current 
contact which automatically cleans off 
any carbon deposit. 

In the wiring diagram, A is the cir- 
cuit breaker ; B, the induction coil, and 
C, the battery. — Contributed by A. Gt. 
Ward, Wilkinsburg, Pa. 



POPULAR MECHANICS 



A Miniature Pepper's Ghost Illusion 



Probably many readers have seen a 
"Peppers Ghost"' illusion at some 
amusement place. As there shown, the 
audience is generally seated in a dark 
room at the end of which there is a 
stage with black hangings. One of the 
audience is invited on to the stage. 
where he is placed in an upright open 
coffin. A white shroud is thrown over 
his body, and his clothes and flesh 
gradually fade away till nothing but 
his skeleton remains, which immedi- 
ately begins to dance a horribly rat- 
tling jig. The skeleton then fades 
away and the man is restored again. 



cupant are seen through the gla; : \ ery 
plainly. The lights in front of the 
glass (behind the scenes) are now 
raised, very gradually as those behind 
the glass are turned down, until it is 
dark there. The perfectly black sur- 
face behind the glass now acts like the 
silver backing for a mirror, and the ob- 
ject upon which the light is now 
turned — in this case the skeleton — is 
reflected in the glass, appearing to the 
audience as if really occupying the 
stage. 

The model, which requires no spe- 
cial skill except that of carpentry, is 




Construction of the Pepper's Ghost Illusion 



The explanation is very simple, says 
the Model Engineer and Electrician. 
Between the audience and the coffin 
is a sheet of transparent glass, inclined 
at an angle so as to reflect objects lo- 
cated behind the scenes, but so clear as 
to be invisible to the audience and the 
man in the coffin. At the beginning 
the stage is lighted only from behind 
the glass. Hence the coffin and its oc- 



constructed as shown in the drawings 
and described below. 

The box containing the stage should 
be 14 in. by T in. by 7| in., inside di- 
mensions. The box need not be made 
of particularly good wood, as the en- 
tire interior, with the exception of the 
glass, figures and lights, should be col- 
ored a dull black. " This can well be 
done by painting with a solution of 



POPULAR MECHANICS 



lampblack in turpentine. If every- 
thing is not black, especially the joints 
and background near A, the illusion 
will be spoiled. 

The glass should be the clearest pos- 
sible, and must be thoroughly cleansed. 
1 1- edges should nowhere be risible, and 
it should be free from scratches and 
imperfections. The figure A should be 
a (loll ahuut 1 in. high, dressed in bril- 
liant, light-colored garments. The 

skeleton IS made of papier mache, and 

can he bought at Japanese .-teres. It 
should preferably he one with arms 
BUBp< Qded by -mall spiral springs, giv- 
ing a limp, loose-jointed effect. The 
method of causing the skeleton to dance 
i> shown in the front view. The figure 
is hung Erom the neck by a blackened 
still' wire attached to the hammer wire 
of an i lectric hell, from which the gong 
has been removed. When the hell 
wnrks he will kick again-t the rear wall, 
ami wave his arms up and down, thus 
giving as realistic a dance as anyone 
could expeel from a skeleton. 

The lights, I. ami M. should he min- 
iature electric lamps, which can be run 
by three dry cell.-. They need to give 
a fairly strong light, especially L, 



which should have 



al tin 



flector to increase its brilliancy and 
prevent its being reflected in the glass. 

Since the stage should be some dis- 
tance from the audience, to aid the 
illusion, the angle of the glass and the 
inclination of the doll, A, has been so 
designed that if the stage is placed 
on a mantle or other high shelf the 
image of A will appear upright to an 
observer sitting in a chair some dis- 
tance away, within the limits of an or- 
dinary room. If it is desired to place 
the box lower down, other angles for 
the image and glass may be found nec- 
essary, but the proper tilt can be found 
readily by experiment. 

The electric connections are so sim- 
ple that they are not shown in the 
drawings. All that is necessary is a 
two-point switch, by which either L or 
M can be placed in circuit with the 
battery, and a press button in circuit 
with the hell and its cell. 

If a gradual transformation is de- 
sired, a double-pointed rheostat could 
be used, so that as one light dims the 
other increases in brilliancy, by the in- 
sertion and removal of resistance coils. 

With a clear glass and a dark room 
this model has proved to he fully as 
bewildering as its prototype. 



The Turning Card Puzzle 



To produce a rotary motion from 
ciprocating motion take a lead pen- 
cil or other 
S moot h stick 
and cut notches 

aboul , : i; or .[ 

in. apart and 
about ,',, in. 
deep. Punch a 
hole exactly 
through the 
nj id 1 e of a 
c a r d, enlarge 
the hole a little 
and put a common pin through it, into 
end of pencil. Hold securely in the 
hand and rub a match or toothpick up 
and down over the notches and the card 
will revolve very fast. With some peo- 
ple to the right ; with others to the left. 




How to Make Four Pictures on One 
Plate 



Secure two extra slides for the plate 
holders and cut one corner out on one 
of them, as shown in Fig. 1. Make a 
hole in the other, as shown in Fig. 2. 
With a lead pencil draw on the; ground 
glass, one line vertical and one hor- 




izontal, each in the center. This will 
divide the ground glass in four equal 
parts. 

Focus the camera in the usual man- 



POPULAR MECHANICS 



ner, but get the picture desired to fill 
only one of the parts on the ground 
Place the plate holder in posi- 
tion and draw the regular slide: -::- 
stitute one of the slides prepared, and 
expose in the usual way. 

If a small picture is to be made in 
the lower left-hand corner of the plate, 
place the prepared slide with the cor- 
ner cut, as shown in Pig. 1. This slide 
may be turned over for the upper left- 
hand corner and then changed for slide 
shown in Fig. 2 for the upper and 
lower right-hand corners. — Contrib- 
uted bv D. L., Elizabeth, >. . J. 




How to Make an Interrupter 



The Wenult interrupter is an in- 
strument much used on large coils and 
is far more efficient than the usual 
form of vibrators. It can also be used 
with success on small coils as well as 
large. Although it is a costly instru- 
ment to purchase, it can be made with 
practically no expense and the con- 
struction is very simple. 

First procure a wide 
mouthed bottle about 4 
in. high, provided with a 
rubber stopper. This 
stopper should be pierced, 
making two holes about 
\ in. in diameter. 

From a sheet of lead 
^e in. in thickness cut 
a piece shaped like A, 
Fig. 1. Common tea 
lead folded several times will serve 
the purpose. "When in the bottle 
this lead should be of such 
that it will only reach half way 
around, as shown in B. To insert the 
lead plate, roll it up so it will pass 
through the neck of the bottle, then 
smooth it out with a small stick until 
it fits against the side, leaving the 
small strip at the top projecting 
through the neck of the bottle. Bend 
this strip to one side and fit in the 
stopper, as shown in C. A small bind- 
ing-post is fastened at the end of the 
strip. 



Having fixed the lead plate in posi- 
tion, next get a piece of glass tube 
having a bore of about 1 / 32 of an inch 
in diameter. A piece of an old ther- 
mometer tube will serve this purpose. 
Insert this tube in the hole in the 
stopper farthest from the lead plate. 
Get a piece of wire that* will fit the 
tube and about 6 in. long, and fasten 
a small binding-post on one end and 
stick the other into the tube. This wire 
should fit the hole in the tube so it 




can be easily moved. In the hole near- 
est the lead plate insert a small glass 
funnel. 

The interrupter as it is when com- 
plete is shown at D, Fig. 1. Having 
finished the interrupter, connect it with 
the electric light circuit as shown in 
Pig. 2. Fill the bottle with water to 
about the line as shown in D, Fig. 1. 
Adjust the wire in the small glass 
tube so that it projects about ^ in. 
sulphuric acid until the water 
level rises about T V in. Turn on the 
current and press the button. B. If 
all adjustments are correct there will 



POPULAR MECHANICS 



be a loud crackling noise from the in- 
terrupter, a violet flame will appear 
at the end of the wire and a hot spark 
will pass between the secondary ter- 
minals. If the interrupter does not 
work at first, add more sulphuric acid 
through the funnel and press the wire 
down a little more into the liquid. A 
piece of wood, A, Fig. 2, should be 
inserted in vibrator to prevent it from 
working. — Contributed by Harold L. 
Jones, Carthage, N. Y. 



A Controller and Reverse for 
Battery Motor 



Secure a cigar or starch box and use 
to make the base, B. Two wood base 
switches, S S, are cut off a little past 



«^w ^_^ 




^ * 


"J B is - n — ~oi 

: i cm 


? ! ; 




O (±ZJD 


! ~r ~~"- : " ■ ' i 


MbPs f< 


It ic 


Sao 


1 l -ir 



Motor Reverse and Controller 

the center and fastened to the base 
with a piece of wood between them. 
The upper switch, S, is connected to 
different equal points on a coil of wire, 
W, while the lower switch, S, is con- 
nected each point to a battery, as 
shown. The reverse switch, K, is made 
from two brass or copper strips fas- 
tened at the top to the base with screws 
and joined together by a piece of hard 
rubber or wood with a small handle 
attached. Connect wires A to the 
armature and wires F to the field of 
the motor. By this arrangement one, 
two or three and so on up until all the 
battery cells are used and different 
points of resistance secured on the coil 
of wire. The reverse lever when moved 
from right to left, or left to right, 



changes the direction of the armature 
in the motor from one way to the other. 
— Contributed by J. Fremont Hilscher, 
Jr., West St. Paul, Minn. 

Athletics for Young Men 



The accompanying illustration shows 
a group of young Americans enjoying 
themselves by building a human pyra- 




The Human Pyramid 

mid on the sands of a New Jersey 
bathing beach between dips in the 
briny deep. 

Don't pull a lamp hung by flexible 
cord to one side with a wire and then 
fasten to a gas pipe. I have seen a 
wire become red hot in this manner. 
If the lamp hung by a cord must be 
pulled over, use a string. 

Don't wrap paper around a lamp 
for a shade. You might go home and 
forget it and a fire might be started 
from the heat. Use a glass or metal 
shade. That is what they are for. 



POPULAR MECHANICS 



e^ 



Amateur Mechanics 



<£ 



A Microscope Without a Lens 



By E. W. D«m> 



heard of the 

pin-ho il the fact that the 

be used to make a 

magnifying 

• i times) will 

- 

i abort 

. and enlarge 

n ith India ink and 
allow it to dry. From a piece of thin 
trent celluloid or mica, cut ont a 
small disc, B, and fasten to I 
having the enlarged bore, by m 

On the other end glue a 
of thin black cardboard, C, and at the 
-'nail hole with the 

point • It i- very im- 

portant that the hole 1> should be very 
>mall, otherwise the image will bo 
blurred. 
To use this microa ope, place a small 
parenl disc, which 
may be moistened to make the 
. and look through the 

It is ; Qg light 

suits, and, a~ in all micro- 
of any power, tin' object Bhould 
be of a transparent nature. 
The principle on which this instru- 
ia illustrated in I 
The apparent diameter of an object ia 
inversely proportional to it- d 
from the eye, i. e., if the distance is 
reduced to one-half, the diameter will 
appear twice as large; if the distance is 
reduced to one-third, the diameter will 
appear three times as large, and 30 on. 
uearesl distance at which the 
average person can Bee an object clear- 
ly is about 6 in., it follow- that the 
diameter of an object | in. from the 
raid appear 8 times the normal 
size. The object would then be magni- 



- diameters, or 6 1 times. (The 

area would appear 6 1 tunes a^ large.) 

Hut an obje< t | in. from the eye ap- 
pear-; so blurred that none of the de- 
tails are discernible, and it is for this 
reason that the pin-hole is employed. 
Viewed through this microscope, a 
tlv's wing appeai-s as large as a person's 

hand, held at arm's length, and has 

the genera] appearance shown in Fig. 

•">. The mother of vinegar examined in 

the same way is seen to be swarming 




with a mass of wriggling little worms, 

and may possibly cause the observer 
to ali-tain from all -alads forever after. 
An innocent looking drop of water, in 

which hay has been soaking for several 
reveals hundreds of little infu- 
soria, darting across the Held in every 

direction. These and hundreds of 

other interesting objects may be ob- 
served in this little instrument, which 
costs little or oothing to make. 



Prince Rupert's Drops 



Prince Rupert's drops are made by 
letting drops of melted glass fall into 
cold water. These drops become oval 
in shape with a tail or neck resembling 
a retort. Their peculiarity is that when 
a small portion of the tail or neck is 



POPULAR MECHANICS 



broken off the whole bursts into powder 
with an explosion and a considerable 
shock is fell by the hand that grasps it. 

How to Balance a Cup on a Knife 

If you were told that you could bal- 
ance a cup one-quarter full of coffee 
on the point of 
a carving knife 
you would hard- 
ly believe it. In- 
sert a cork in the 
handle of a cup 
tightly, says the 
Detroit Free 
Press. Stick two 
of the prongs of 
a fork into the 
cork, in the posi- 
l i on shown in the sketch. This ar- 
rangement lowers the center of gravity 
of the whole, and if you have a steady 
ham], you may now place the cup on 
the point of the knife. 




Photographs Lightning Flash 




enabled me to obtain the correct focus 
quickly the first night an electrical 
storm occurred, with a result, as you 
can see, to be proud of. The exposure 
was taken about 8:30 o'clock in the 
evening with the camera set due south. 
I had often thought of the possibilities 
of photographing flashes but never 
gave it a trial until after reading the 
above mentioned article." 

How to Make Small Gear Wheels 
Without a Lathe 



To make small models sundry small 
gears and racks are required, either 
cut for the place or by using the parts 
from an old clock. With no other tools 
than a hack-saw, some files, a compass 
and with the exercise of a little pa- 
tience and moderate skill, very good 
teeth mav be cut on blank wheels. 



This interesting letter and lightning 
flash photograph were received from 
Fred M. Roberts, Paterson, X. J., and 
describe how he profited from an article 
published in Popular Mechanics. 

"Keceiving a suggestion from an 
article published in Popular Mechan- 
ics on the subject of photographing 
lightning flashes, 1 took my camera out 
and focusing it on the setting sun 
marked its position on the scale. This 




Brilliant Cloud Effect 



Making Model Wheels 

First take the case of a small gear- 
wheel, say 1 in. outside diameter and 
T V in. thick, with twenty.-four teeth. 
Draw a circle on paper, the same diam- 
eter as the wheel. Divide the circum- 
ference into the number of parts de- 
sired, by drawing diameters, Fig. 1. 
The distance A B will be approximately 
the pitch. Now describe a smaller cir- 
cle for the base of the teeth and half- 
way between these circles may be taken 
as the pitch circle. 

Now describe a circle the same size as 
the largest circle on a piece of iVin. 
sheet metal, and having cut it out and 
filed it up to this circle, fasten the 



POPULAR MECHANICS 



marked-out paper circle accurately over 
9 A-outs can now be 
made down the diameters to the smaller 
circle with the aid of a saw 
., made from iVin. i"- 
or iron. This guide should haw a l>ev- 
.. to lay along 
the line on which the saw-cot is to be 
made. The straight-edge, CD, should 
be set back one-half the thick] 

that the center of 

the blade, when flat against it, will be 

over the line F G. A -mall clearance 

most be made to allow the 

teeth of the saw to 



cut should be deeper on the side which 
has the larger diameter. To cut a 
rack the pitch should be marked along 
the side, and the guide and saw used 
re (Pig. 4j. 



How to Make a Paper Phonograph 
Horn 




Details of Phonograph Horn 

The guide should then be placed 
along one of the diameters and held in 
position until gripped in 
3. The first tooth may now 
care being taken to keep the blade of 
the saw flat up to the guiding edge. 
The Model Engineer, London, says if 
this is done and the saw-guide well 
made, the cut will be central on the 
line, and if the marking out is cor- 
rect the teeth will be quite uniform all 
the way round. A small ward file will 
be needed to finish off the teeth to their 
proper shape and thickness. 

In making a worm wheel the cuts 
must be taken in a sloping direction, 
the slope and pitch depending on the 
slope and pitch of the worm thread, 
which, though more difficult, may also 
be cut with a hacksaw and file. 

A bevel wheel should be cut in the 
same manner as the spur wheel, but the 



Secure a piece of tubing about If in. 

it will fit the connection to the 

reproducer, and wrap a quantity of 

heavy thread around one end as shown 

in the en b. A, Fig. 1. Form 

ne of heavy paper, 

y in. long and 3 in. in 

diameter, at the I 

end with the smaller end 

to fit the diameter of the 

tube A, making it three 

ply thick and gluing the 

layers together. Attach 

this cone on the tube A 

where the thread has 

rapped with glue, 

as shown in Fig, 2. Fig. 

also an en 
sketch. Make ten pieces 
1 ft. 10 in. in 
length and 3 in. wide 
from the thin boards of 
a biscuit or cracker box. Cut an arc of 
a circle in them on a radius of 2 ft. 
•. Make a stick 10-sided, 12 
in. long, that will fit loosely in the 
tube. A, to which nail the 10 pi© - - 
shown in Fig. 4, connecting the bottom 
■ - pieces, using care to keep them 
at equal distances apart and in a circle 
whose diameter is about 2 ft. 

The cone is placed over the stick as 
shown by the dotted lines in Fig. 4 and 
temporarily fastened in position. Cut 
out paper sections (Fig. 5) that will 
cover each space between the 10 pieces, 
allowing 1 in. on one side and the top 
in which to cut slits that will form 
pieces to overlap the next section and 
to attach with glue. Fasten the sec- 
tions all around in like manner. The 
next course is put on in strips over- 
lapping as shown at B, Fig. 6. Finish 
by putting on sections in the same way 



POPULAR MECHANICS 



u the . making it three-ply 

thick. Remove the form, trim to rait 
and glue a piece of paper over the 
When the glue is thoroughly 
hardened, pul on two coats of white 
and one of blue paint. shading it to 
-uit and Btriping it with gold bronae. 
Contributed bj B. II. Eaver, Hous- 
ton, i 



How to Bind Magazines 



An • bind Popul 

chanics in volumes oi a year each is to 
oee mi order am! tie 
them aecurely both ways with a Btrong 

! wall to put 
two it threi 

s bite paper, cut to 

■nt and ba< 

1 nap tin- whole in a 
r clamp w ith two 

'i with 
the 

With a sharp 
saa i nl a -In in the 

rod i I 

!i. deep 
ami Blanting a- Bhoa d at 

A ami I'.. I 

-tout cloth, aboul 8 or l" 

in. long ami a- wide as the distance 

■i the bottoms of the -awed slit-. 

Lav these over the hack edge of the 

■ !v through the -lits 

with a string thread— wrapping and 

eeral timer- 1 1 

If you hfl 

paper knife, trim both ends and the 

front edge; this makes a much nicer 

h.i..k. hut if the paper knife cannot be 
used, clamp the whole between two 

hoards and -aw off the edges, boards 

and all. smoothly, with a tine -aw. 

Cut four piece- of cardhoard. } in. 
longer and J in. narrower than the 
n.- after they have been 
trimmed. Lav one piece of the board 
on the hook and under the doth strips, 
rdinary flour paste and paste the 
strip- to the cardboard and then rub 



pa-te all over the top of the strips and 
the board. Bub paste over one side of 
another piece of hoard and put it on 
top of the tir-t hoard and -trips press- 
Ing down firmly so that the strips are 
held securely between the two boards. 

Turn the book over and do the same 
with the other two boards. 

After the paste has dried a few 

minute- take a piece of strong cloth, 
duck or linen, fold and cut it 1 in. 
.dl around than the hook, leav- 
ing the Folded edge uncut. Rub pa-te 
over one of the hoard backs ami lay 
one end of the cloth on it. smoothing 
and creasing as shown at A. Pig. :k 
Turn the book over and pa-te the other 




l»rocess ol home-Made Binding 



Bide. The back edges should have a 
good coal of paste and a -trip of paper 
the w idth of the thickness of the pack 
pasted on before pasting the cloth to 

• ond hoard back. 

Cut off the corners and fold over 
the edgi - of the doth, pasting them 
down ( Fig. •) i. Rub pa-te on one side 
of a fly leaf ami press the back down 
on it. Turn the book over and paste 
a fly leaf to the other back after the 

Of the cloth have been folded 

'low n. The backs must not lie opened 
until the fly leaves are thoroughly dry. 
Trim and tuck in the end- of the strip 
at the hack edge. 

When fixed this way your magazines 
make one of the nio-t valuable volumes 
yon can possibly add to your library of 
mechanical books. — Contributed by 
Joseph N. Parker, Bedford City, Va. 



LOFC. 



HANI. ^ 



now K) MAKE \ COMBINATION LOCK 



■ 




. 

dear through the thickness ->f the 
..r. if the disci be made •>( thick wood, only 
enough i" ■lion t! • 

IhiHi ■ ' , ill. Ii«»l'- 

Dter of ea< ! 
In the 
Indent ■'• 

the 
centei 

I small pin 'i in 

ould i'< 
driving it 

3 If. in. Into tli«' 
disc, and allowing 

1 16 in 

.•!< sh..\\ 

On t! • 

b _ b1 the lo- 
cation shown by 
B, a 
leather, 

metal, ' t in. long, 
Vv, in. wide and 
1/16 in. thick. 




should \.-r\ -mall 

placed in i><> 

; > thej must i..- faced t" 

between them, 

*» tii.it the pin driven in tii.- Oral disc 

; i..- caught by the bll -■!' 
leather fastened on the second dlac (which 

'.. til.- -halt I ; 

. - I., i..- turned 
• baa tv- 
r enough for the piece >>f leather 
:iii tii.- pin. 

the dlac device, 

ahould t n tii.- Inside of the door; but a 

. uhi ex- 



LU 



hand through a ,-i.>t in tin- door, BO that the 
bolt ma] be -\i>\ back and forth from the 
■ tii.- door, when the discs are in 
position i" allow it to slide. Pig. 
■ in.- slide ix.it. with 
i»t the Indents in the 'lis.-. 
bows ii..w .i block may ii<- attached 
t«> the Inside "f tin- door as a support for 
tin- pin ..r shaft on which the disc revolve, 
and leaving room between the blocfi ami the 
<l<...r for tii.- die I ows the shaft, 

V» in. in diameter, with a cross handle on 
the end which is to be on the outside of 
tin- door. This handle serves not only to 
turn the shaft, but also as an Indicator on 
the dial fai«-. The dial face may be paint- 
ed on the door. Bhowing figures from 1 to 12. 

When yon have put the device together, 

go mi tin- Inside of the dOOX and then turn 

the 9haft to the left until the piece of 
leather on tin- second disc catches the pin 

driven into the first disc and carries the 
disc around until tin- indent in it is in the 
proper position to allow the slide bolt to 



»u 



POPULAR MECHANICS 



open. Go to the outside of the door now, and 
note at what figure on the dial face the indi- 
cator rests. This figure is the first figure in 
your combination. The slide bolt will not 
open as yet, however, as the second disc is 



a 



c 



Fig. 5 

not in position. To keep the first, or loose, 
disc in position while the second disc is 
being turned, a steel spring should be made 
to real on its surface, acting as a "brake." 
The shaft must not be turned in the op- 
poslte direction, or to the right, until the 
indent in the second disc conies into posi- 
tion alongside the first. The point at which 



; i '&$ 


IP 


-3" 


— » 1 ; 


O 


o 


o 



Fig. 6 

the Indicator resta now is the second num- 
ber in your combination. 

To open the lock, turn the shaft several 
revolutions to the left and let the indicator 
rest at the first number in your combina- 
tion. Then turn to the right until the indi- 
cator rests at the second number of the 
combination; draw back the slide bolt and 



Fig. 1 [ 

open the door. The combination can be 
easily and frequently changed.— Contributed 
by A. L. Burkhart, .Morton Park, 111. 



Volume II. Shop Notes for 1906, con- 
tains short cuts and practical information 
for men of every craft. Contains 228 pages, 
667 articles, 500 illustrations. Price 50 cts. 



HOW TO MAKE A GROCERY 
MEMORANDUM 

A handy device for the kitchen is a gro- 
cery memorandum by which the house- 
wife can remind herself of what she wishes 
from the store when the order boy makes 
his morning call. 

Procure a piece of white wood, 9 in. long 
by 3 in. wide, and 
plane off the edges 
and surface. Then, 
with the aid of a 
scroll saw, saw out 
the top as shown in 
the illustration. This 
done, file it even with 
a wood file, then 
sandpaper it. 

With a medium 
pencil, not too hard, 
draw the lines for 
the names. These 
lines should be about 
% in. apart. At the 
right hand side of 
each name make a 
hole for a peg. 

Make the peg 
board or shelf 2*4 in. long and iy 2 in. 
wide and round off the corners. At the 
bottom of the list board chisel out a 
hole 3 16 in. deep for the shelf. Glue the 
shelf in and make the pe^s of a size to 
fit in the holes. Finish with two coats of 
shellac 

\\ hen the housekeeper thinks of some- 
thing she must order, .she puts a peg op- 
posite the name of that article, and thus 
has no trouble in remembering it. The board 
would be very pretty done in burnt wood. 
—Contributed by Walter A. Springborg, 
Elgin, 111. 



BANNC POWOER O 



TRAP FOR SMALL ANIMALS 



This is a box trap with glass sides and 
back, the panes of glass being held in place 
by brads placed on 
both sides. The ani- 
mal does not fear to 
enter the box, be- 
cause he can see 
through it; when he 
enters, however, and 
touches the bait the 
lid is released and, dropping, shuts him in. 
This is one of the easiest traps to build 
and is usually successful. 




POPULAR MECHANICS 



EASY METHOD OF ELECTRO=PLATING 



Before proceeding to electroplate with 
copper, silver or other metal, clean the arti- 
cles thoroughly, as the least sp..t of grease 
or dirt will prevent the deposit from adher- 
ing'. Then polish the articles and rub them 

over with a cloth and tine pnmice powder. 
to roughen the surface Slightly. Finally, to 
remove all traces of grease, dip the articles 
to be plated in a boiling potash solution 
made by dissolving 4 02. American ash in 
1% pt. of water. Do not touch tin' work 
with the bands again. To avoid touching 
it, bang tbe articles on the wires by which 
they are to be suspended in the plating 
hath, before dipping them in the potash so- 
lution; then hold them by the wires under 
running water for ten minutes to remove 
the potash. 

For plating with copper prepare tbe fol- 
lowing solution: 4 oz. copper sulphate dis- 
solved in 12 oz. water; add strong ammonia 
solution until no more green crystals are 
precipitated. Then add more ammonia and 
stir until the green crystals are re-dissolved 
giving an intense blue solution. Add slowly 
a strong solution of potassium cyanide until 
the blue color disappears, leaving a clean 
solution; add potassium cyanide again, 
about one-fourth as much in bulk as used 
in the decolorizing process. Then make the 
solution up to 2 qt with water. With an 
electric pressure of 3.5 to 4 volts, this will 
give an even deposit of copper. 

A solution for silver-plating may be pre- 
pared as follows: Dissolve % oz. of com- 
mercial silver nitrate in 8 oz. of water, and 
slowly add a strong solution of potassium 
cyanide until no more white precipitate 
is thrown down. Then pour the liquid 
off and wash the precipitate carefully. 
This is best done by filling tbe bottle with 
water, shaking, allowing precipitate to set- 
tle and then pouring off the water. Repeat 
six times. Having finished washing the pre- 
cipitate, slowly add to it a solution of po- 
tassium cyanide until all the precipitate is 
dissolved. Then add an excess of potassium 
cyanide — about as much as was used in dis- 
solving the precipitate — and make the solu- 
tion up to 1 qt. with water. This solution, 
with an electric pressure of 2 to 4 volts, 



will give a good white coat of silver in 
twenty minutes to half-an-hour; use 2 volts 
lor large articles, and -1 volts for very small 
"Mrs. if more solution is required, it is only 
necessary to double all given quantities. 
Before silver-plating, such metals as iron, 



copptr for 
coppv plotinq 




Electroplating Apparatus 

lead, pewter, zinc, must be coated with cop- 
per in the alkaline copper bath described, 
and then treated as copper. On brass, cop- 
per, German silver, nickel and such metals, 
silver can be plated direct. The deposit of 
silver will be dull and must be polished, 
says the Model Engineer, London. The best 
method is to use a revolving scratch brush; 
if one does not possess a buffing machine, a 
hand scratch brush is good. Take quick, 
light strokes. Polish the articles finally 
with ordinary plate powder. 

The sketch shows how to suspend the ar- 
ticles in the plating bath. If accumulators 
are used, which is advised, be sure to con- 
nect the positive (or red) terminal to the 
piece of silver hanging in tbe bath, and the 
negative (or black) terminal to the article 
to be plated. Where Bunsen cells are used, 
the carbon terminal takes the place of the 
positive terminal of the accumulator. 



POPULAR MECHANICS 



SlflPLE SWITCH FOR REVERSING 
A CURRENT 



Take two strips of copper or brass and 
fasten them together by means of gutta 




Simple Current Reversing Switch 

percha (Fig. 1); also provide them with a 
handle. Saw out a rectangular block about 
one and one-half times as long as the brass 
strips and fasten to it at each end two 
forked pieces of copper or brass, as in Fig. 
2. Fasten on the switch lever as at A and 
B, Fig. 2, so that it can rotate about these 
points. Connect the wires as shown in 
Fig. 3. To reverse, throw the lever from 
one end of the block to the other.— Contrib- 
uted by R. L. Thomas, San Marcos, Tex. 



INTERESTING ELECTRICAL 
EXPERIMENT 



The materials necessary for performing 
this experiment are: Telephone receiver, 
transmitter, some wire and some carbons, 
either the pencils for arc lamps, or ones 
taken from old dry batteries will do. 

Run a line from the inside of the house 
to the inside of some other building and 
fasten it to one terminal of the receiver. 
To the other terminal fasten another piece 



( 


pc cavit 


f\ 




t \_y 


m: 




c-Gnoum c-cwo* 


- 1 

























of wire and ground it on the water faucet 
in the house. If there is no faucet in the 
house, ground it with a large piece of zinc. 

Fasten the other end to one terminal of 
the transmitter and from the other terminal 
of the same run a wire into the ground. 
The ground here should consist either of a 
large piece of carbon, or several pieces 
bound tightly together. 

If a person speak into the transmitter, one 
at the receiver can hear what is said, even 
though there are no batteries in the cir- 
cuit. It is a well known fact that two tele- 
phone receivers connected up in this way 
will transmit words between two persons, 
for the voice vibrating the diaphragm causes 
an inductive current to flow and the other 
receiver copies these vibrations. But in this 
experiment, a transmitter which induces no 
current is used. Does the carbon and the 
zinc and the moist earth form a battery? — 
Contributed by Wm. J. Slattery, Emsworth, 
Pennsylvania. 



HOME-MADE GRENET BATTERY 



A Unique Battery 



Procure an ordinary carbon-zinc sal am. 
inoniac battery and remove the zinc rod. If 
the battery has been used before, it is bet- 
ter to soak the carbon cylinder for a few 
hours to remove any remaining crystals of 
sal ammoniac from its pores. 

The truncated, conical zinc required is 
known as a fuller's zinc and can be bought 
at any electrical supply dealer's, or, it may 
be cast in a sand mould from scrap zinc 
or the worn-out zinc rods from sal am- 
moniac batteries. It should be cast on the 
end of a piece of No. 14 copper wire. Amal- 
gamation is not necessary for the zinc one 
buys, but if one casts his own zinc, it is 
necessary to amalgamate it or coat it With 
mercury. This may be done as follows: 

Dip a piece of rag in a diluted solution 
of sulphuric acid (acid 1 part, water 16 
parts); rub the zinc well, at the same time 
allowing a few drops of mercury to fall on 
a spot attacked by the acid. The mercury 
will adhere, and if the rubbing is contin- 
ued so as to spread the mercury, it will 
cover the entire surface of the zinc, giving 
it a bright, silvery appearance. 

Next procure what is known as a wire 
connector. This is a piece of copper tube 
about 1% in. long having two thumb 
screws, one on each end on opposite sides 
(Fig. 2). The upper screw is to connect 
the battery wire, the lower one to raise 



POPULAR MECHANICS 



and lower the zinc. The battery is now 
complete, -and the solution (Fig. l) must be 
prepared. Proceed as follows: 

In 32 oz. of water dissolve 4 oz. potas- 
sium bichromate. When the bichromate 
has all dissolved, add slowly, stirring con- 



VIEWQFWIRE 
CONNECT OR 



screw. This prevents the zinc wasting 
away when no current is being used.— 
Contributed by H. C. Meyer, 132 West Lo- 
gan St., Germantown, Phila., Pa. 




Details of Home- Made Battery 

stantly, 4 oz. sulphuric acid. Do not add 
the acid too quickly or the heat generated 
may breaii the vessel containing the solu- 
tion. Then pour the solution into the bat- 
tery jar, until it is within 3 in. of the top. 
Thread the wire holding the zinc through 
the porcelain insulator of the carbon cylin- 
der and also through the wire connector. 
Pull the zinc up as far as it will go and 
tighten the lower thumb screw so that it 
holds the wire secure. Place the carbon in 
the jar. If the solution touches the zinc, 
some of it should he poured out. To de- 
termine whether or not the zinc is touched 
by the solution, take out the carbon and 
lower the zinc. If it is wet, there is too 
much liquid in the jar. The battery is now 
ready for use. 

To cause a flow of electricity, lower the 
zinc until it almost touches the bottom of 
the jar and connect an electric bell or other 
electrical apparatus by means of wires to 
the two binding posts. 

This battery when first set up gives a 
current of about two volts. It is useful for 
running induction coils, or small electric 
motors. When through using the battery, 
raise the zinc and tighten the lower thumb 



SlflPLE ELECTRIC LOCK 



The illustration shows an automatic lock 
operated by electricity, requiring a strong 
magnet, but no weights or strings which 
greatly simplifies the device over many 
others of the kind. 

The weight of the long arm, L, is just a 
trifle greater than the combined weights of 
the short anus, A and S. The fulcrum of 
the lever is at C, where there is a staple. 
The lever swings on one arm of the staple 
and the other arm is so placed that when 
the lever is in an upright position, with the 
long arm at L', it will not fall because of its 
greater weight but stays in the position 
shown. The purpose of this is to leave the 
short arm, A. when in position at A', within 
the reach of the magnet. Arm L rests on 
an [/-shaped hook, H; in this position the 
door is locked. 

To unlock the door, press the button, B. 
The momentum acquired from the magnet 
by the short arms, A and S, is sufficient to 
move the long arm up to the position of L'. 
To lock the door, press the button and the 



il*-' 


uaaR 


m^ B p 

A II 




11 t 


%f" 


Hi 





Lock Operated by a Magnet 

momentum acquired from the magnet by 
the short arms, now at A' and S' is suffi- 
cient to move the long arm down from L' 
to the position at L.— Contributed by Benja- 
min Kubelsky, 597 W. Harrison street, Chi- 
cago, 111. 



Shop Notes Series ^ 



Popular Mechanics ^flOp NOlcS OCrlcS ofYcarBooks 

C One of these books is issued the first of each year, and is a reprint of all the 
articles which have been published during the year past, in our "Shop 
Notes Department." 

200 Pages Vol. I, "SllOp NotCS for 1905" 385 Illustrations 

228 Pages Vol. II, "Shop NoteS for 1906" 555 Illustrations 

228 Pages Vol III,"ShOp NoteS for 1907" 580 Illustrations 

212 Pages Vol. IV/'SIlOp NoteS for 1908" 536 Illustrations 

C. These books are a perfect gold mine of information for every one interested 
in mechanics, or who uses tools for pleasure or as an occupation. Of equal 
value and help to the professional mechanic and the amateur. 

C These articles are the cream of the experience of years, of hundreds of the 
most successful mechanics in the country. There is nothing on the market 
equal to these books at five times their price. 

C. The Popular Mechanics Shop Notes Series TELLS EASY WAYS TO DO HARD 
THINGS, and like Popular Mechanics, is "Written so you can understand it." 

C These books are indexed very fully and with great care. 

CL The subjects treated cover every department of mechanics, with useful time 
saving "kinks" for engineers, firemen, carpenters, machinists, plumbers, 
painters, iron and wood workers, electricians of all kinds, masons, and in 
fact all the trades. 

C " WORTH ITS WEIGHT IN GOLD" is a frequent expression from our readers, 
and one young mechanic in the far west who started a repair shop for himself, 
says he owes his success to " Popular Mechanics Shop Notes." Many a time 
when a customer brought in a job new to him, he consulted his " Shop Notes," 
which told him how to do it. 

C Each volume contains entirely different matter from that published in the 
other. A set of these books covering several years will make an encyclopedia 
of priceless value to the owner. 

Trice 50 Cents per Volume, Postpaid 

For Sale by all Newsdealers or can be ordered direct from the Publishers 

POPULAR MECHANICS :: :: :: CHICAGO 



25c. 



A BOOK FOR BOYS 



Ho 

i ing Tackle- 

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:.— Permanent Camps 
Build Them— Bow to 

.. ' Make a Water Blcv- 
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Windmill— How to Build an Ice 
ir Alarm- A 
M-vhanlcal . 
How to Make 
Boot-Black 

"Antique"! 

Materials— Lettering a Clock Dial 
—How to Make a Windmill of One 
or Two Horsepower— How to 
Make a Trap fur Rabbits, Rats 
". ike a Small 
Searchlight — Kites . >f M my 
Kinds and How to Make Them— 
Jutf FUnlng— 1I"W to Do Orna- 
mental Iron Work— Ornamental 
- 
—How to Make a Propelling Ve- 
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escope— How to Mak 
loons — How to Make a Hecto- 
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25cents bv 

THE PUBLISHERS 



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MECHANICS 

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YOUNG AMERICA 

How to Build 

BOATS. WATER MOTORS. WIND Mil 1 S, SEARCHLIGHT. 
ELECTRIC BURGLAR ALARM. KE BOAT. W.\ HER 
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STREET CAR UNfi. ETC, 

The Directions are Plain and Complete 



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cles -A WaterCaudlestick— Bov's 
Hand-Power Auto. How Made— 
U.'W to M ike a Pair of Dumb- 
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-Things a Boy Can Make Out of 
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—How to Makea Miniature steam 
Turbine— How to See Through 
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to Make a Turbine Engine— How 
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1 60 Washington St. 
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ELECTRICITY. The study of. and Its laws for be- 
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with explanations of simple mathematics as applied 
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ELECTRIC BELLS AND ALARMS. How to Install 
them. By N. H. Schneider. Including batteries, wire 
and wiring, circuits', pushes, bells, burglar alar 
high and low water alarms, fire alarms, thermosti 
annunciators, and the locating and remedving of faults. 
With 58 original diagrams. 25 cents, postpaid. 

MODERN PRIMARY BATTERIES. Their cons 
tion. use and maintenance, including batteries for tele- 
phones, telegraphs, motors, electric lights, induction 
coils, and for all experimental work. Bv N. " 
Schneider. 94 pages. 55 illustrations. The best 
latest American book on the subject. 25 cents. 

EXPERIMENTING WITH INDUCTION COLLS. 
S. Norrie. author of "Induction Colls and Coil Mak- 
ing." A most instructive little book, full of practical 
and interesting experiments, fully explained in plain 
language with numerous hints and suggestions for even- 
ing entertainments. Arranged under the following 
headings: Introduction; The Handling of Bnhmkorff 
Co 'J: Experiments with Sparks; Effects In the 
Vacmmm; Induction a*d Wlrelwa Telegraphy. With 



[In the press.] 25 cen's, 

ELECTRIC GAS LIGHTING. How to Install electric 
gas igniting apparatus. Including the Jump spark and 
multiple systems for all purposes. Also the care and 
selection of suitable batteries, wiring and repairs. By 
EL S. Norrie. 101 pages, 57 Illustrations, paper. 25 
cents, postpaid. 

THE LOCOMOTIVE, simply explained. A first In- 
troduction to the study of the locomotive engine, their 
designs, construction and erection, with a short cate- 
chism, and 26 illustrations. 25 cents, postpaid. 

WOODWORK JOINTS. How to make and where to 
use them; Including mortise and tenon joints, lap 
joints, dovetail joints, glue joints and scarfing joints. 
With a chapter on circular woodwork, revised and 
enlarged edition, 101 pages, 178 illustrations. 25 cents, 
postpaid. 

SMALL ELECTRICAL MEASURING INSTRU- 
MENTS, describing the making and using of the dif- 
ferent Instruments, fully Illustrated. 25 cents, post- 
paid. 

METAL WORKING TOOLS AND THEIR USES. A 

Handbook for Young Engineers and Apprentices. 

Shows how to use simple tools required in metal work 

| ing and model making. Illustrated. 25 cents, post- 

THE SLIDE VALVE. Simply explained for working 
engineers. Fullv illustrated. 25 cents, postpaid. 

DIAGRAM OF CORLISS ENGINE. A large engrav- 
ing giving a longitudinal section of the Corliss engine 
cylinder, showing relative positions of the piston, 
steam valves, exhaust valves, and wrist plates when 
cut-oft" takes place at % stroke for each 15 degrees of 
the circle. With full particulars. Reach-rods and 
rock shafts. The circle explained. Wrist plates and 
eccentrics. Explanation of figures, etc. Printed on 
heavy paper, size 13 In. x 19 In. 25 cents', postpaid. 

INDUCTION COILS. A practical handbook on the 
construction and use of shock and spark coils. With 35 
illustratio ns. 2 5 cents, postpaid. 

JOINT WIPING. Practical hints for beginners In 
plumbing. Fully Illustrated. 25 cents, postpaid. 



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